Science.gov

Sample records for coevolutionary competitive exclusion

  1. Neanderthal Extinction by Competitive Exclusion

    PubMed Central

    Banks, William E.; d'Errico, Francesco; Peterson, A. Townsend; Kageyama, Masa; Sima, Adriana; Sánchez-Goñi, Maria-Fernanda

    2008-01-01

    Background Despite a long history of investigation, considerable debate revolves around whether Neanderthals became extinct because of climate change or competition with anatomically modern humans (AMH). Methodology/Principal Findings We apply a new methodology integrating archaeological and chronological data with high-resolution paleoclimatic simulations to define eco-cultural niches associated with Neanderthal and AMH adaptive systems during alternating cold and mild phases of Marine Isotope Stage 3. Our results indicate that Neanderthals and AMH exploited similar niches, and may have continued to do so in the absence of contact. Conclusions/Significance The southerly contraction of Neanderthal range in southwestern Europe during Greenland Interstadial 8 was not due to climate change or a change in adaptation, but rather concurrent AMH geographic expansion appears to have produced competition that led to Neanderthal extinction. PMID:19107186

  2. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Competitive exclusion culture. 529.469 Section 529... Competitive exclusion culture. (a) Specifications. Each packet of lyophilized culture contains either 2,000 or... contents of one 2,000-dose packet of lyophilized culture. Mix thoroughly. (2) For 5,000-dose packet, add...

  3. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Competitive exclusion culture. 529.469 Section 529... Competitive exclusion culture. (a) Specifications. Each packet of lyophilized culture contains either 2,000 or... contents of one 2,000-dose packet of lyophilized culture. Mix thoroughly. (2) For 5,000-dose packet,...

  4. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Competitive exclusion culture. 529.469 Section 529... Competitive exclusion culture. (a) Specifications. Each packet of lyophilized culture contains either 2,000 or... contents of one 2,000-dose packet of lyophilized culture. Mix thoroughly. (2) For 5,000-dose packet,...

  5. Competitions between prosocial exclusions and punishments in finite populations

    NASA Astrophysics Data System (ADS)

    Liu, Linjie; Chen, Xiaojie; Szolnoki, Attila

    2017-04-01

    Prosocial punishment has been proved to be a powerful mean to promote cooperation. Recent studies have found that social exclusion, which indeed can be regarded as a kind of punishment, can also support cooperation. However, if prosocial punishment and exclusion are both present, it is still unclear which strategy is more advantageous to curb free-riders. Here we first study the direct competition between different types of punishment and exclusion. We find that pool (peer) exclusion can always outperform pool (peer) punishment both in the optional and in the compulsory public goods game, no matter whether second-order sanctioning is considered or not. Furthermore, peer exclusion does better than pool exclusion both in the optional and in the compulsory game, but the situation is reversed in the presence of second-order exclusion. Finally, we extend the competition among all possible sanctioning strategies and find that peer exclusion can outperform all other strategies in the absence of second-order exclusion and punishment, while pool exclusion prevails when second-order sanctioning is possible. Our results demonstrate that exclusion is a more powerful strategy than punishment for the resolution of social dilemmas.

  6. Plant competition and exclusion with optimizing individuals.

    PubMed

    Finnoff, David; Tschirhart, John

    2009-11-21

    Most models of plant competition represent competition as taking place between species when realistically competition takes place between individuals. We model individual plants as optimally choosing biomass in order to maximize net energy that is directed into reproduction. Competition is for access to light and a plant that grows more biomass adds to the leaf area index, creating negative feedback in the form of more self shading and shading of its neighbors. In each period and for given species densities, simultaneous maximization by all plants yields an equilibrium characterized by optimum biomasses. Between periods the net energies plants obtain are used to update the densities, and if densities change the equilibrium changes in the subsequent period. A steady state is attained when all plants have net energies that just allow for replacement. Four main predictions of the resource-ratio theory of competition are obtained, providing behavioral underpinnings for species level models. However, if individual plant parameters are not identical across species, then the predictions do not follow. The optimization framework yields many other predictions, including how specific leaf areas and resource stress impact biomass and leaf area indices.

  7. Competitive Exclusion: Comments on Survival and Extinction of Species

    ERIC Educational Resources Information Center

    Jaeger, Robert G.

    1974-01-01

    Examines aspects of competitive exclusion, which develops when two species jointly utilize a vital resource that is in short supply. When this occurs, one of the species will eventually eliminate the other from the habitat where their distributions overlap, unless one or both species evolve differences that reduce competition. (JR)

  8. Species competition: coexistence, exclusion and clustering

    PubMed Central

    Hernández-García, Emilio; López, Cristóbal; Pigolotti, Simone; Andersen, Ken H.

    2009-01-01

    We present properties of Lotka–Volterra equations describing ecological competition among a large number of interacting species. First we extend previous stability conditions to the case of a non-homogeneous niche space, i.e. that of a carrying capacity depending on the species trait. Second, we discuss mechanisms leading to species clustering and obtain an analytical solution for a state with a lumped species distribution for a specific instance of the system. We also discuss how realistic ecological interactions may result in different types of competition coefficients. PMID:19620117

  9. Coevolutionary computation.

    PubMed

    Paredis, J

    1995-01-01

    This article proposes a general framework for the use of coevolution to boost the performance of genetic search. It combines coevolution with yet another biologically inspired technique, called lifetime fitness evaluation (LTFE). Two unrelated problems--neural net learning and constraint satisfaction--are used to illustrate the approach. Both problems use predator-prey interactions to boost the search. In contrast with traditional "single population" genetic algorithms (GAs), two populations constantly interact and co-evolve. However, the same algorithm can also be used with different types of co-evolutionary interactions. As an example, the symbiotic coevolution of solutions and genetic representations is shown to provide an elegant solution to the problem of finding a suitable genetic representation. The approach presented here greatly profits from the partial and continuous nature of LTFE. Noise tolerance is one advantage. Even more important, LTFE is ideally suited to deal with coupled fitness landscapes typical for coevolution.

  10. Quantifying Competitive Exclusion and Competitive Release in Ecological Communities: A Conceptual Framework and a Case Study

    PubMed Central

    Henkin, Zalmen; Kadmon, Ronen

    2016-01-01

    A fundamental notion in community ecology is that local species diversity reflects some balance between the contrasting forces of competitive exclusion and competitive release. Quantifying this balance is not trivial, and requires data on the magnitude of both processes in the same system, as well as appropriate methodology to integrate and interpret such data. Here we present a novel framework for empirical studies of the balance between competitive exclusion and competitive release and demonstrate its applicability using data from a Mediterranean annual grassland where grazing is a major mechanism of competitive release. Empirical data on the balance between competitive exclusion and competitive release are crucial for understanding observed patterns of variation in local species diversity and the proposed approach provides a simple framework for the collection, interpretation, and synthesis of such data. PMID:27536943

  11. Quantifying Competitive Exclusion and Competitive Release in Ecological Communities: A Conceptual Framework and a Case Study.

    PubMed

    Segre, Hila; DeMalach, Niv; Henkin, Zalmen; Kadmon, Ronen

    2016-01-01

    A fundamental notion in community ecology is that local species diversity reflects some balance between the contrasting forces of competitive exclusion and competitive release. Quantifying this balance is not trivial, and requires data on the magnitude of both processes in the same system, as well as appropriate methodology to integrate and interpret such data. Here we present a novel framework for empirical studies of the balance between competitive exclusion and competitive release and demonstrate its applicability using data from a Mediterranean annual grassland where grazing is a major mechanism of competitive release. Empirical data on the balance between competitive exclusion and competitive release are crucial for understanding observed patterns of variation in local species diversity and the proposed approach provides a simple framework for the collection, interpretation, and synthesis of such data.

  12. Coexistence and exclusion of stochastic competitive Lotka-Volterra models

    NASA Astrophysics Data System (ADS)

    Nguyen, Dang H.; Yin, George

    2017-02-01

    This work derives sufficient conditions for the coexistence and exclusion of a stochastic competitive Lotka-Volterra model. The conditions obtained are close to necessary. In addition, convergence in distribution of positive solutions of the model is also established. A number of numerical examples are given to illustrate our results.

  13. Stochastic competitive exclusion leads to a cascade of species extinctions.

    PubMed

    Capitán, José A; Cuenda, Sara; Alonso, David

    2017-04-21

    Community ecology has traditionally relied on the competitive exclusion principle, a piece of common wisdom in conceptual frameworks developed to describe species assemblages. Key concepts in community ecology, such as limiting similarity and niche partitioning, are based on competitive exclusion. However, this classical paradigm in ecology relies on implications derived from simple, deterministic models. Here we show how the predictions of a symmetric, deterministic model about the way extinctions proceed can be utterly different from the results derived from the same model when ecological drift (demographic stochasticity) is explicitly considered. Using analytical approximations to the steady-state conditional probabilities for assemblages with two and three species, we demonstrate that stochastic competitive exclusion leads to a cascade of extinctions, whereas the symmetric, deterministic model predicts a multiple collapse of species. To test the robustness of our results, we have studied the effect of environmental stochasticity and relaxed the species symmetry assumption. Our conclusions highlight the crucial role of stochasticity when deriving reliable theoretical predictions for species community assembly.

  14. Survival analysis of stochastic competitive models in a polluted environment and stochastic competitive exclusion principle.

    PubMed

    Liu, Meng; Wang, Ke; Wu, Qiong

    2011-09-01

    Stochastic competitive models with pollution and without pollution are proposed and studied. For the first system with pollution, sufficient criteria for extinction, nonpersistence in the mean, weak persistence in the mean, strong persistence in the mean, and stochastic permanence are established. The threshold between weak persistence in the mean and extinction for each population is obtained. It is found that stochastic disturbance is favorable for the survival of one species and is unfavorable for the survival of the other species. For the second system with pollution, sufficient conditions for extinction and weak persistence are obtained. For the model without pollution, a partial stochastic competitive exclusion principle is derived.

  15. Competitive coexistence and competitive exclusion for a nonlinear community with delay effect and impulsive birth

    NASA Astrophysics Data System (ADS)

    Liu, Yanping; Zhang, Feng; Wei, Jianzhou

    2016-12-01

    By constructing a population model of multi-species competition, a community with nonlinear interaction relationship is investigated, in which the species' response delay and environmental fluctuation effects (i.e., seasonal fluctuation of resource supplies and species' reproductive activities) on population are considered. Firstly, the conditions about competitive coexistence (i.e., persistence of all species) and competitive exclusion (i.e., only partial of species, but not all, keep persistence) of the community are established, and the underlying ecological mechanism of these results are analyzed. Secondly, by some illustrative examples, the interactive effects of nonlinear competition, species' response delay and environmental fluctuation on the structure of community are explored. It is demonstrated that small response delay and slight deviation of nonlinear competition indexes from 1 have little impact on the coexistence of community, but acute changes have distinct negative influence on community coexistence. This reveals to us that parameter perturbations of natural communities should keep in an appropriate range, which is of great significance in conservation and restoration biology.

  16. 47 CFR 101.1317 - Competitive bidding procedures for mutually exclusive MAS EA applications.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Competitive bidding procedures for mutually exclusive MAS EA applications. 101.1317 Section 101.1317 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... License Requirements § 101.1317 Competitive bidding procedures for mutually exclusive MAS EA...

  17. Competitive exclusion, beta diversity, and deterministic vs. stochastic drivers of community assembly.

    PubMed

    Segre, Hila; Ron, Ronen; De Malach, Niv; Henkin, Zalmen; Mandel, Micha; Kadmon, Ronen

    2014-11-01

    Species diversity has two components - number of species and spatial turnover in species composition (beta-diversity). Using a field experiment focusing on a system of Mediterranean grasslands, we show that interspecific competition may influence the two components in the same direction or in opposite directions, depending on whether competitive exclusions are deterministic or stochastic. Deterministic exclusions reduce both patch-scale richness and beta-diversity, thereby homogenising the community. Stochastic extinctions reduce richness at the patch scale, but increase the differences in species composition among patches. These results indicate that studies of competitive effects on beta diversity may help to distinguish between deterministic and stochastic components of competitive exclusion. Such distinction is crucial for understanding the causal relationship between competition and species diversity, one of the oldest and most fundamental questions in ecology.

  18. COEXISTENCE, EXCLUSION, OR NEUTRALITY? A META-ANALYSIS OF COMPETITION BETWEEN AEDES ALBOPICTUS AND RESIDENT MOSQUITOES

    PubMed Central

    Juliano, Steven A.

    2012-01-01

    Competition experiments estimating the relative effects of inter- and intraspecific competition can help to resolve whether interspecific competition results in coexistence or exclusion. For mosquitoes, most such experiments have focused on invasive Aedes albopictus and its interactions with resident Aedes. A meta-analysis of such experiments tested whether the effect of interspecific competition is greater than, less than, or equal to that of intraspecific competition, and whether competitive outcomes are dependent on food quality. For A. albopictus and A. aegypti, there was significant context dependence, with interspecific competitive advantage for A. albopictus with low food quality, and competitive equivalence with high food quality. Meta-analysis of survivorship yielded more significant effects than did estimated rate of increase. Competitive effects and competitive responses of each species yielded similar results. This meta-analysis suggests competitive exclusion of A. aegypti by A. albopictus, and is thus consistent with field sampling, qualitative reviews, and interpretations from individual publications. For A. albopictus and A. triseriatus, most results indicated competitive equivalence and no context dependence, and are thus contrary to previous qualitative reviews and to interpretations from individual publications. For both pairs of species, published results suitable for meta-analysis remain scarce, and better experimental designs and improved analysis and reporting of statistical results are needed. Greater emphasis needs to be placed on estimating species’ inter- and intra-specific competitive effects, rather than the more common, but theoretically less interesting, competitive responses. Experiments without low-density controls (i.e., replacement series) are inadequate for comparing competitive effects and responses. PMID:23482823

  19. COEXISTENCE, EXCLUSION, OR NEUTRALITY? A META-ANALYSIS OF COMPETITION BETWEEN AEDES ALBOPICTUS AND RESIDENT MOSQUITOES.

    PubMed

    Juliano, Steven A

    2010-06-01

    Competition experiments estimating the relative effects of inter- and intraspecific competition can help to resolve whether interspecific competition results in coexistence or exclusion. For mosquitoes, most such experiments have focused on invasive Aedes albopictus and its interactions with resident Aedes. A meta-analysis of such experiments tested whether the effect of interspecific competition is greater than, less than, or equal to that of intraspecific competition, and whether competitive outcomes are dependent on food quality. For A. albopictus and A. aegypti, there was significant context dependence, with interspecific competitive advantage for A. albopictus with low food quality, and competitive equivalence with high food quality. Meta-analysis of survivorship yielded more significant effects than did estimated rate of increase. Competitive effects and competitive responses of each species yielded similar results. This meta-analysis suggests competitive exclusion of A. aegypti by A. albopictus, and is thus consistent with field sampling, qualitative reviews, and interpretations from individual publications. For A. albopictus and A. triseriatus, most results indicated competitive equivalence and no context dependence, and are thus contrary to previous qualitative reviews and to interpretations from individual publications. For both pairs of species, published results suitable for meta-analysis remain scarce, and better experimental designs and improved analysis and reporting of statistical results are needed. Greater emphasis needs to be placed on estimating species' inter- and intra-specific competitive effects, rather than the more common, but theoretically less interesting, competitive responses. Experiments without low-density controls (i.e., replacement series) are inadequate for comparing competitive effects and responses.

  20. 'Excellence' and Exclusion: The Individual Costs of Institutional Competitiveness.

    PubMed

    Watermeyer, Richard; Olssen, Mark

    A performance-based funding system like the United Kingdom's 'Research Excellence Framework' (REF) symbolizes the re-rationalization of higher education according to neoliberal ideology and New Public Management technologies. The REF is also significant for disclosing the kinds of behaviour that characterize universities' response to government demands for research auditability. In this paper, we consider the casualties of what Henry Giroux (2014) calls "neoliberalism's war on higher education" or more precisely the deleterious consequences of non-participation in the REF. We also discuss the ways with which higher education's competition fetish, embodied within the REF, affects the instrumentalization of academic research and the diminution of academic freedom, autonomy and criticality.

  1. Coevolutionary aesthetics in human and biotic artworlds.

    PubMed

    Prum, Richard O

    2013-01-01

    This work proposes a coevolutionary theory of aesthetics that encompasses both biotic and human arts. Anthropocentric perspectives in aesthetics prevent the recognition of the ontological complexity of the aesthetics of nature, and the aesthetic agency of many non-human organisms. The process of evaluative coevolution is shared by all biotic advertisements. I propose that art consists of a form of communication that coevolves with its own evaluation. Art and art history are population phenomena. I expand Arthur Danto's Artworld concept to any aesthetic population of producers and evaluators. Current concepts of art cannot exclusively circumscribe the human arts from many forms of non-human biotic art. Without assuming an arbitrarily anthropocentric perspective, any concept of art will need to engage with biodiversity, and either recognize many instances of biotic advertisements as art, or exclude some instances of human art. Coevolutionary aesthetic theory provides a heuristic account of aesthetic change in both human and biotic artworlds, including the coevolutionary origin of aesthetic properties and aesthetic value within artworlds. Restructuring aesthetics, art criticism, and art history without human beings at the organizing centers of these disciplines stimulate new progress in our understanding of art, and the unique human contributions to aesthetics and aesthetic diversity.

  2. Competitive Exclusion of Dendroctonus rufipennis Induced by Pheromones of Ips tridens and Dryocoetes affaber (Coleoptera: Scolytidae)

    Treesearch

    Therese M. Poland; John H. Borden

    1998-01-01

    We tested the feasibility of competitive exclusion as a potential management tactic for the spruce beetle, Dendroctonus rufipennis Kirby, using pre-attack baiting with pheromones of 2 secondary species, Ips tridens Mannerheim and Dryocoetes affaber Mannerheim. Spruce beetle attack densities, gallery lengths per...

  3. 47 CFR 101.1317 - Competitive bidding procedures for mutually exclusive MAS EA applications.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Competitive bidding procedures for mutually exclusive MAS EA applications. 101.1317 Section 101.1317 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Multiple Address Systems...

  4. Coevolutionary Free Lunches

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.; Macready, William G.

    2005-01-01

    Recent work on the foundations of optimization has begun to uncover its underlying rich structure. In particular, the "No Free Lunch" (NFL) theorems [WM97] state that any two algorithms are equivalent when their performance is averaged across all possible problems. This highlights the need for exploiting problem-specific knowledge to achieve better than random performance. In this paper we present a general framework covering most search scenarios. In addition to the optimization scenarios addressed in the NFL results, this framework covers multi-armed bandit problems and evolution of multiple co-evolving agents. As a particular instance of the latter, it covers "self-play" problems. In these problems the agents work together to produce a champion, who then engages one or more antagonists in a subsequent multi-player game In contrast to the traditional optimization case where the NFL results hold, we show that in self-play there are free lunches: in coevolution some algorithms have better performance than other algorithms, averaged across all possible problems. However in the typical coevolutionary scenarios encountered in biology, where there is no champion, NFL still holds.

  5. Exclusivity strategies and opportunities in view of the Biologics Price Competition and Innovation Act.

    PubMed

    Gaudry, Kate S

    2011-01-01

    Government-provided exclusivity periods provide pharmaceutical companies with incentives to invest in new drugs. Meanwhile, encouraging competition serves another worthy goal of improving the affordability of medications. Decades ago, the Hatch-Waxman Act set forth provisions attempting to balance these objectives in the context of small-molecule drugs. Recently, the Biologics Price Competition and Innovation Act was enacted to meet similar aims in the context of biologic drugs. This article presents a detailed comparison of these two Acts. While the Acts share many global similarities (e.g., providing exclusivity terms and abbreviated approval processes), many differences are also apparent when analyzing details of the provisions. One area of great departure between the Acts is the requirements of how a generic or follow-on applicant must address patents covering a reference product. After describing these differences, the article presents predictions of how reference product sponsors will adapt their patent-prosecution strategies in view of the new Biologics Act.

  6. In vitro selection of enteric microflora for potential use as a competitive exclusion culture against Campylobacter in poultry

    USDA-ARS?s Scientific Manuscript database

    The administration of nonpathogenic microflora in neonatal poultry has been employed to reduce or eliminate the colonization of enteric pathogens. This concept, also called competitive exclusion (CE), although effective against Salmonella, has not consistently worked against Campylobacter. Most CE...

  7. Cost modeling of biocontrol strains Pseudomonas chlororaphis and P. flurorescens for competitive exclusion of Salmonella enterica on tomatoes

    USDA-ARS?s Scientific Manuscript database

    Biological control of foodborne pathogens may complement postharvest intervention measures to enhance food safety of minimally processed produce. The purpose of this research was to develop cost model estimates for application of competitive exclusion process (CEM) using Pseudomonas chlororaphis and...

  8. Within-host competitive exclusion among species of the anther smut pathogen

    PubMed Central

    Gold, Alexander; Giraud, Tatiana; Hood, Michael E

    2009-01-01

    Background Host individuals represent an arena in which pathogens compete for resources and transmission opportunities, with major implications for the evolution of virulence and the structure of populations. Studies to date have focused on competitive interactions within pathogen species, and the level of antagonism tends to increase with the genetic distance between competitors. Anther-smut fungi, in the genus Microbotryum, have emerged as a tractable model for within-host competition. Here, using two pathogen species that are frequently found in sympatry, we investigated whether the antagonism seen among genotypes of the same species cascades up to influence competition among pathogen species. Results Sequential inoculation of hosts showed that a resident infection most often excludes a challenging pathogen genotype, which is consistent with prior studies. However, the challenging pathogen was significantly more likely to invade the already-infected host if the resident infection was a conspecific genotype compared to challenges involving a closely related species. Moreover, when inter-specific co-infection occurred, the pathogens were highly segregated within the host, in contrast to intra-specific co-infection. Conclusion We show evidence that competitive exclusion during infection can be greater among closely related pathogen species than among genotypes within species. This pattern follows from prior studies demonstrating that genetic distance and antagonistic interactions are positively correlated in Microbotryum. Fungal vegetative incompatibility is a likely mechanism of direct competitive interference, and has been shown in some fungi to be effective both within and across species boundaries. For systems where related pathogen species frequently co-occur in the same host populations, these competitive dynamics may substantially impact the spatial segregation of pathogen species. PMID:19422703

  9. Competitive exclusion by autologous antibodies can prevent broad HIV-1 antibodies from arising

    DOE PAGES

    Luo, Shishi; Perelson, Alan S.

    2015-08-31

    The past decade has seen the discovery of numerous broad and potent monoclonal antibodies against HIV type 1 (HIV-1). Eliciting these antibodies via vaccination appears to be remarkably difficult, not least because they arise late in infection and are highly mutated relative to germline antibody sequences. Here, using a computational model, we show that broad antibodies could in fact emerge earlier and be less mutated, but that they may be prevented from doing so as a result of competitive exclusion by the autologous antibody response. We further find that this competitive exclusion is weaker in infections founded by multiple distinctmore » strains, with broadly neutralizing antibodies emerging earlier than in infections founded by a single strain. Our computational model simulates coevolving multitype virus and antibody populations. Broadly neutralizing antibodies may therefore be easier for the adaptive immune system to generate than previously thought. As a result, if less mutated broad antibodies exist, it may be possible to elicit them with a vaccine containing a mixture of diverse virus strains.« less

  10. Competitive exclusion by autologous antibodies can prevent broad HIV-1 antibodies from arising

    SciTech Connect

    Luo, Shishi; Perelson, Alan S.

    2015-08-31

    The past decade has seen the discovery of numerous broad and potent monoclonal antibodies against HIV type 1 (HIV-1). Eliciting these antibodies via vaccination appears to be remarkably difficult, not least because they arise late in infection and are highly mutated relative to germline antibody sequences. Here, using a computational model, we show that broad antibodies could in fact emerge earlier and be less mutated, but that they may be prevented from doing so as a result of competitive exclusion by the autologous antibody response. We further find that this competitive exclusion is weaker in infections founded by multiple distinct strains, with broadly neutralizing antibodies emerging earlier than in infections founded by a single strain. Our computational model simulates coevolving multitype virus and antibody populations. Broadly neutralizing antibodies may therefore be easier for the adaptive immune system to generate than previously thought. As a result, if less mutated broad antibodies exist, it may be possible to elicit them with a vaccine containing a mixture of diverse virus strains.

  11. Competitive exclusion by autologous antibodies can prevent broad HIV-1 antibodies from arising.

    PubMed

    Luo, Shishi; Perelson, Alan S

    2015-09-15

    The past decade has seen the discovery of numerous broad and potent monoclonal antibodies against HIV type 1 (HIV-1). Eliciting these antibodies via vaccination appears to be remarkably difficult, not least because they arise late in infection and are highly mutated relative to germline antibody sequences. Here, using a computational model, we show that broad antibodies could in fact emerge earlier and be less mutated, but that they may be prevented from doing so as a result of competitive exclusion by the autologous antibody response. We further find that this competitive exclusion is weaker in infections founded by multiple distinct strains, with broadly neutralizing antibodies emerging earlier than in infections founded by a single strain. Our computational model simulates coevolving multitype virus and antibody populations. Broadly neutralizing antibodies may therefore be easier for the adaptive immune system to generate than previously thought. If less mutated broad antibodies exist, it may be possible to elicit them with a vaccine containing a mixture of diverse virus strains.

  12. Antimicrobial susceptibility patterns of competitive exclusion bacteria applied to newly hatched chickens.

    PubMed

    Wagner, R Doug; Cerniglia, Carl E

    2005-07-25

    Competitive exclusion (CE) products are mixtures of obligate and facultative anaerobic bacteria applied to poultry hatchlings for prevention of Salmonella colonization. These mixtures have the potential to introduce bacteria with undesirable antimicrobial drug resistance traits into the human food supply. Antimicrobial drug susceptibilities of 27 obligate and facultative anaerobes isolated from a commercial CE product were evaluated with a microdilution minimal inhibitory concentration (MIC) assay. Bacteroides distasonis and Bacteroides fragilis isolates were resistant to tetracycline and other antimicrobial drugs. An Escherichia coli isolate was resistant to four antimicrobial drugs: erythromycin, penicillin, vancomycin, and tylosin. Erythromycin-resistant enterococci and vancomycin-resistant Lactococcus lactis isolates in the CE product were detected. These findings suggest that more work needs to be done to assess the potential effects of CE product use in poultry on the food supply.

  13. Species colonisation, not competitive exclusion, drives community overdispersion over long-term succession.

    PubMed

    Li, Shao-Peng; Cadotte, Marc W; Meiners, Scott J; Hua, Zheng-Shuang; Jiang, Lin; Shu, Wen-Sheng

    2015-09-01

    Ecological communities often transition from phylogenetic and functional clustering to overdispersion over succession as judged by space-for-time substitution studies. Such a pattern has been generally attributed to the increase in competitive exclusion of closely related species with similar traits through time, although colonisation and extinction have rarely been examined. Using 44 years of uninterrupted old-field succession in New Jersey, USA, we confirmed that phylogenetic and functional clustering decreased as succession unfolded, but the transition was largely driven by colonisation. Early colonists were closely related and functionally similar to residents, while later colonists became less similar to the species present. Extirpated species were generally more distantly related to residents than by chance, or exhibited random phylogenetic/functional patterns, and their relatedness to residents was not associated with time. These results provide direct evidence that the colonisation of distant relatives, rather than extinction of close relatives, drives phylogenetic and functional overdispersion over succession.

  14. The interplay between aridity and competition determines colonization ability, exclusion and ecological segregation in the heteroploid Brachypodium distachyon species complex.

    PubMed

    Rey, Pedro J; Manzaneda, Antonio J; Alcántara, Julio M

    2017-07-01

    A higher competitive advantage of polyploid plants compared with their parental diploids is frequently invoked to explain their establishment success, colonization of novel environments and cytotypic ecological segregation, yet there is scarce experimental evidence supporting such hypotheses. Here, we investigated whether differential competitive ability of species of the Brachypodium distachyon (Poaceae) species complex, a model system for genomic, ecological and evolutionary studies of temperate grasses, contributes to explaining their ecological segregation as well as their coexistence in diploid/allotetraploid contact zones. We conducted two field experiments in dry and humid localities to evaluate the tolerance to competition of diploids and allotetraploids in densely occupied environments, and to parameterize models of intra- and intercytotype competition as a mechanism for species exclusion/coexistence. We provide experimental evidence supporting the hypothesis that, under natural field conditions, allotetraploids have superior ecological success compared with one of their parental diploids in terms of both colonizing competitive habitats and intercytotypic competition, with the balance of intra/intercytotype competition favoring polyploid population establishment. These findings, together with previous data on ecogeographic segregation and adaptive response to water stress, suggest that the interplay between aridity and competitive outcome determines the ability to colonize competitive environments, the exclusion of diploids, especially in arid localities, and species geographic segregation. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  15. Herbivore exclusion drives the evolution of plant competitiveness via increased allelopathy.

    PubMed

    Uesugi, Akane; Kessler, André

    2013-05-01

    The 'Evolution of Increased Competitive Ability (EICA)' hypothesis predicts the evolution of plant invasiveness in introduced ranges when plants escape from their natural enemies. So far, the EICA hypothesis has been tested by comparing plant vigor from native and invasive populations, but these studies are confounded by among-population differences in additional environmental factors and/or founder effects. We tested the major prediction of EICA by comparing the competitive ability (CA) of Solidago altissima plants originating from artificial selection plots in which we manipulated directly the exposure to above-ground herbivores. In a common garden experiment, we found an increase in inter-specific, but not intra-specific, CA in clones from herbivore exclusion plots relative to control plots. The evolutionary increase in inter-specific CA coincided with the increased production of polyacetylenes, whose major constituent was allelopathic against a heterospecific competitor, Poa pratensis, but not against conspecifics. Our results provide direct evidence that release from herbivory alone can lead to an evolutionary increase in inter-specific CA, which is likely to be mediated by the increased production of allelopathic compounds in S. altissima. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  16. Competitive exclusion over broad spatial extents is a slow process: Evidence and implications for species distribution modeling

    USGS Publications Warehouse

    Yackulic, Charles B.

    2016-01-01

    There is considerable debate about the role of competition in shaping species distributions over broad spatial extents. This debate has practical implications because predicting changes in species' geographic ranges in response to ongoing environmental change would be simpler if competition could be ignored. While this debate has been the subject of many reviews, recent literature has not addressed the rates of relevant processes. This omission is surprising in that ecologists hypothesized decades ago that regional competitive exclusion is a slow process. The goal of this review is to reassess the debate under the hypothesis that competitive exclusion over broad spatial extents is a slow process.Available evidence, including simulations presented for the first time here, suggests that competitive exclusion over broad spatial extents occurs slowly over temporal extents of many decades to millennia. Ecologists arguing against an important role for competition frequently study modern patterns and/or range dynamics over periods of decades, while much of the evidence for competition shaping geographic ranges at broad spatial extents comes from paleoecological studies over time scales of centuries or longer. If competition is slow, as evidence suggests, the geographic distributions of some, perhaps many species, would continue to change over time scales of decades to millennia, even if environmental conditions did not continue to change. If the distributions of competing species are at equilibrium it is possible to predict species distributions based on observed species–environment relationships. However, disequilibrium is widespread as a result of competition and many other processes. Studies whose goal is accurate predictions over intermediate time scales (decades to centuries) should focus on factors associated with range expansion (colonization) and loss (local extinction), as opposed to current patterns. In general, understanding of modern range dynamics would be

  17. Comparative genomics of Lactobacillus crispatus suggests novel mechanisms for the competitive exclusion of Gardnerella vaginalis.

    PubMed

    Ojala, Teija; Kankainen, Matti; Castro, Joana; Cerca, Nuno; Edelman, Sanna; Westerlund-Wikström, Benita; Paulin, Lars; Holm, Liisa; Auvinen, Petri

    2014-12-05

    Lactobacillus crispatus is a ubiquitous micro-organism encountered in a wide range of host-associated habitats. It can be recovered from the gastrointestinal tract of animals and it is a common constituent of the vaginal microbiota of humans. Moreover, L. crispatus can contribute to the urogenital health of the host through competitive exclusion and the production of antimicrobial agents. In order to investigate the genetic diversity of this important urogenital species, we performed a comparative genomic analysis of L. crispatus. Utilizing the completed genome sequence of a strain ST1 and the draft genome sequences of nine other L. crispatus isolates, we defined the scale and scope of the pan- and core genomic potential of L. crispatus. Our comparative analysis identified 1,224 and 2,705 ortholog groups present in all or only some of the ten strains, respectively. Based on mathematical modeling, sequencing of additional L. crispatus isolates would result in the identification of new genes and functions, whereas the conserved core of the ten strains was a good representation of the final L. crispatus core genome, estimated to level at about 1,116 ortholog groups. Importantly, the current core was observed to encode bacterial components potentially promoting urogenital health. Using antibody fragments specific for one of the conserved L. crispatus adhesins, we demonstrated that the L. crispatus core proteins have a potential to reduce the ability of Gardnerella vaginalis to adhere to epithelial cells. These findings thereby suggest that L. crispatus core proteins could protect the vagina from G. vaginalis and bacterial vaginosis. Our pan-genome analysis provides insights into the intraspecific genome variability and the collective molecular mechanisms of the species L. crispatus. Using this approach, we described the differences and similarities between the genomes and identified features likely to be important for urogenital health. Notably, the conserved genetic

  18. Cost modeling of pseudomonoas fluorescens and pseudomonoas chlororphis biocontrol for competitive exclusion of salmonella enterica on tomatoes

    USDA-ARS?s Scientific Manuscript database

    Biocontrol measures may enhance postharvest interventions, however; published research on process-based models for biocontrol of foodborne pathogens on produce is limited. The aim of this research was to develop cost model estimates for competitive exclusion process using Pseudomonas fluorescens and...

  19. Inhibition of Staphylococcus aureus by antimicrobial biofilms formed by competitive exclusion microorganisms on stainless steel.

    PubMed

    Son, Hyeri; Park, Sunhyung; Beuchat, Larry R; Kim, Hoikyung; Ryu, Jee-Hoon

    2016-12-05

    The goal of this study was to develop a desiccation resistant antimicrobial surface using biofilm of competitive exclusion (CE) microorganism inhibitory to Staphylococcus aureus. We isolated 161 microorganisms from soils, foods, and food-contact surfaces that are inhibitory to S. aureus. Among them, three CE microorganisms (Streptomyces spororaveus strain Gaeunsan-18, Bacillus safensis strain Chamnamu-sup 5-25, and Pseudomonas azotoformans strain Lettuce-9) exhibiting strong antibacterial activity and high growth rates were selected for evaluation. These isolates formed biofilms within 24h on stainless steel coupons (SSCs) immersed in Bennet's broth and tryptic soy broth at 25°C. Cells in these biofilms showed significantly (P≤0.05) enhanced resistance to a desiccation (43% relative humidity [RH]) compared to those attached to SSCs but not in biofilms. The antimicrobial activities of biofilms formed by these isolates on SSCs against S. aureus at 25°C and 43% RH were determined. Compared to SSCs lacking biofilms formed by CE microorganisms, populations of S. aureus on SSCs harboring CE biofilms were significantly lower (P≤0.05). Results indicate that persistent antimicrobial activity against S. aureus on stainless steel surfaces can be achieved by the presence of biofilms of CE microorganisms. This information will be useful when developing strategies to improve the microbiological safety of foods during storage, processing, and distribution by facilitating the development of effective antimicrobial food-contact surfaces.

  20. Detection of bacteria from a cecal anaerobic competitive exclusion culture with an immunoassay electrochemiluminescence sensor

    NASA Astrophysics Data System (ADS)

    Beier, Ross C.; Young, Colin R.; Stanker, Larry H.

    1999-01-01

    A competitive exclusion (CE) culture of chicken cecal anaerobes has been developed and used in this laboratory for control of Salmonella typhimurium in chickens. The CE culture consists of 29 different species of micro-organisms, and is known as CF3. Detection of one of the CF3 bacteria, Eubacteria, and S. typhimurium were demonstrated using a commercial immunomagnetic (IM) electrochemiluminescence (ECL) sensor, the ORIGENR Analyzer. Analysis was achieved using a sandwich immunoassay. Bacteria were captured on antibody- conjugated 280 micron sized magnetic beads followed by binding of reporter antibodies labelled with ruthenium (II) tris(dipyridyl) chelate [Ru(bpy)32+]. The magnetic beads were then trapped on an electrode in the reaction cell of the ORIGENR Analyzer by a magnet, and the ECL was evoked from Ru(bpy)32+ on the tagged reporter antibodies by an electrical potential at the electrode. Preliminary IM-ECL assays with Eubacteria yielded a detection limit of 105 cfu/mL. Preliminary IM-ECL assays with S. typhimurium yielded a similar detection limit of 105 cfu/mL.

  1. Control of Salmonella Enteritidis in turkeys using organic acids and competitive exclusion product.

    PubMed

    Milbradt, E L; Zamae, J R; Araújo Júnior, J P; Mazza, P; Padovani, C R; Carvalho, V R; Sanfelice, C; Rodrigues, D M; Okamoto, A S; Andreatti Filho, R L

    2014-08-01

    To evaluate the use of organic acids (OAs) and competitive exclusion (CE) product administered continuously in the feed and transiently in drinking water on the control of Salmonella enterica subspecie enterica serotype Enteritidis (SE) prior to slaughter. The influence of treatments were evaluated on pH, population of the lactic acid bacteria (LAB) and bacteria of the family Enterobacteriaceae, concentration of volatile fatty acids and SE colonization in the crop and caecum. The birds were challenged with SE 24 h before being slaughtered, and then, the caeca and crop were removed and subjected to SE counts. Continuous administration of OAs reduced the population of bacteria from the Enterobacteriaceae family in both crop and caecum, positively influenced the butyric acid concentration and reduced SE colonization in the caecum. The diet supplemented with CE product positively influenced the quantity of LAB in the crop and caecum, elevated the butyric acid concentration and reduced both Enterobacteriaceae quantity and SE colonization in the caecum. There was no effect from administering the treatments via drinking water on the variables measured. Continuous supplementation in feed with OAs and CE product reduced SE colonization of the caeca. Supplementation of OAs and CE product in diet to turkeys can reduce the SE load, potentially leading to a lower contamination risk of meat during slaughter. © 2014 The Society for Applied Microbiology.

  2. Competitive exclusion in a vector–host epidemic model with distributed delay†

    PubMed Central

    Cai, Li-Ming; Martcheva, Maia; Li, Xue-Zhi

    2013-01-01

    A multi-strain model of a vector-borne disease with distributed delay in the vector and the host is investigated. It is shown that if the reproduction number of the model ℛ0 < 1, the unique disease-free equilibrium is globally asymptotically stable. Without loss of generality, strain one is assumed to have the largest reproduction number. In this case, the dominance equilibrium of strain one is shown to be locally stable. The basic reproduction number for a strain i (ℛ0i) is written as a product of the reproduction number of the vector (ℛvi) and the reproduction number of the host (ℛih), i.e. ℛi0 = ℛihℛvi. The competitive exclusion principle is derived under the somewhat stronger condition that if strain one maximizes both the reproduction number of the host ℛhi < ℛh1, i ≠ 1 and the reproduction number of the vector ℛvi < ℛv1, i ≠ 1, strain one dominance equilibrium is globally asymptotically stable. AMS Subject Classification: 92D30 PMID:23421610

  3. Competitive exclusion within the predator community influences the distribution of a threatened prey species.

    PubMed

    Byholm, Patrik; Burgas, Daniel; Virtanen, Tarmo; Valkama, Jari

    2012-08-01

    While much effort has been made to quantify how landscape composition influences the distribution of species, the possibility that geographical differences in species interactions might affect species distributions has received less attention. Investigating a predator-prey setting in a boreal forest ecosystem, we empirically show that large-scale differences in the predator community structure and small-scale competitive exclusion among predators affect the local distribution of a threatened forest specialist more than does landscape composition. Consequently, even though the landscape parameters affecting Siberian flying squirrel (Pteromys volans) distribution (prey) did not differ between nest sites of the predators Northern Goshawks (Accipiter gentilis) and Ural Owls (Strix uralensis), flying squirrels were heterospecifically attracted by goshawks in a region where both predator species were present. No such effect was found in another region where Ural Owls were absent. These results provide evidence that differences in species interactions over large spatial scales may be a major force influencing the distribution and abundance patterns of species. On the basis of these findings, we suspect that subtle species interactions might be a central reason why landscape models constructed to predict species distributions often fail when applied to wider geographical scales.

  4. Dynamic use of wetlands by black ducks and mallards: evidence against competitive exclusion

    USGS Publications Warehouse

    McAuley, D.G.; Clugston, D.A.; Longcore, J.R.

    2004-01-01

    The decline of the American black duck (Anas rubripes) has been attributed to competition from mallards (A. platyrhynchos) that led to exclusive use of fertile wetlands by mallards. Data from annual breeding waterfowl surveys provide instantaneous, single observations of breeding pairs, which are used to estimate breeding population size and evaluate the condition of habitat. Data from these surveys have been used to document habitat use by black ducks and mallards. We used quiet-observation surveys from elevated platforms to study sympatric black ducks and mallards in northern Maine during the breeding season. Our objectives were to document occupancy of wetlands by breeding black ducks and mallards throughout the day during prenesting and early nesting periods to determine whether 1) wetlands were occupied by only a single species, 2) pairs of the same species occupied wetlands throughout the period, and 3) single observations of short duration adequately determine numbers and species using a wetland. We observed ducks at 5-minute intervals from elevated platforms on wetland margins to determine numbers and species of indicated pairs using each wetland over time. We visited 80% of the wetlands >2 times, with mean total time per wetland averaging 267 minutes. For each wetland we determined the most frequently observed grouping of black ducks and mallards from all combinations recorded during all intervals (e.g., 1 black duck [BO] pair during 9 intervals; 2 mallard [MA] pairs and 1 BO pair during 22 intervals; 0 pairs during 3 intervals). A single pair, a lone male, or no ducks were recorded during 34% of the 5-minute intervals. For wetlands with >2 hours of observations (n=65), all but 2 were used by >2 different combinations of ducks. On most wetlands, the most frequent grouping was observed during 2 hours were used by both species, random visits detected both species on only 27 wetlands. Our data do not support assertions that the mallard has caused the decline

  5. Salmonellae reduction in poultry by competitive exclusion bacteria Lactobacillus salivarius and Streptococcus cristatus.

    PubMed

    Zhang, Guodong; Ma, Li; Doyle, Michael P

    2007-04-01

    The objective of this study was to develop a defined competitive exclusion bacteria (CE) culture that will prevent or substantially reduce Salmonella colonization of poultry. The efficacy of 56 potential CE isolates in preventing or reducing Salmonella colonization in chickens was determined. These potential CE were perorally administered to day-of-hatch chicks at 10(6) to 10(8) CFU per chick, and salmonellae were subsequently administered by gavage 2 days later at 5.5 x 10(3) to 5.0 x 10(4) CFU per chick. Feeding chickens an overnight CE culture of Lactobacillus salivarius strains Salm-9, List40-1,8, or List40-41 reduced Salmonella carriage in cecal contents by 2.10, 2.52, and 2.20 log CFU/g (average of three trials), respectively. The percentages of Salmonella-positive chickens after receiving these treatments were 35, 31, and 35% respectively, compared with 84% for the untreated control. A mixture of these three isolates had a similar effect when compared with the results of the individual isolates. A mixture of Streptococcus cristatus List40-13 and L. salivarius List40-41 reduced Salmonella carriage from 90 to 65% and 88 to 31% in two feeding trials, and by 2.2 and 4 log CFU/g of cecal contents of chickens. In conclusion, CE isolates L. salivarius Salm-9, List40-18, and List40-41 and S. cristatus List40-13 either individually or in combination were effective in significantly preventing Salmonella colonization of chickens.

  6. Inhibition of Campylobacter jejuni colonization in chicks by defined competitive exclusion bacteria.

    PubMed Central

    Schoeni, J L; Wong, A C

    1994-01-01

    Campylobacter enteritis in humans has been linked to consumption of chicken. Reducing Campylobacter jejuni colonization in chickens can potentially reduce Campylobacter infections in humans. In this study, the reduction of C. jejuni colonization in chicks by oral administration of defined competitive exclusion (CE) cultures, 2.5% dietary carbohydrates, or CE cultures and carbohydrates was examined. Prevention, elimination, or direct challenge of Campylobacter infection was simulated by administering treatments before, after, or at the same time as that of the Campylobacter inoculation. Additionally, the effect of maintaining high levels of protective bacteria was evaluated by administering CE cultures on days 1 and 4 (booster treatment). All treatments reduced C. jejuni colonization. Protection by aerobically grown CE cultures was not statistically different from that by anaerobically grown CE cultures. A combination of Citrobacter diversus 22, Klebsiella pneumoniae 23, and Escherichia coli 25 (CE 3) was the most effective CE treatment. Maintaining high numbers of CE isolates by administering CE boosters did not increase protection. The greatest reduction of Campylobacter colonization was observed in schemes to prevent or eliminate C. jejuni infection. C. jejuni was not detected in the ceca of birds receiving the prevention treatment, CE 3 with mannose, representing a 62% reduction in the colonization rate. The protection factor (PF), a value combining the colonization rate and the level of infection, for CE 3 with mannose was high (> 13.2). Fructo-oligosaccharides alone strongly prevented Campylobacter colonization. Only 8% of the chicks in this group were colonized, with a PF of > 14.3.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8017915

  7. Dynamic landscape models of coevolutionary games.

    PubMed

    Richter, Hendrik

    2017-02-24

    Players of coevolutionary games may update not only their strategies but also their networks of interaction. Based on interpreting the payoff of players as fitness, dynamic landscape models are proposed. The modeling procedure is carried out for Prisoner's Dilemma (PD) and Snowdrift (SD) games that both use either birth-death (BD) or death-birth (DB) strategy updating. The main focus is on using dynamic fitness landscapes as a mathematical model of coevolutionary game dynamics. Hence, an alternative tool for analyzing coevolutionary games becomes available, and landscape measures such as modality, ruggedness and information content can be computed and analyzed. In addition, fixation properties of the games and quantifiers characterizing the interaction networks are calculated numerically. Relations are established between landscape properties expressed by landscape measures and quantifiers of coevolutionary game dynamics such as fixation probabilities, fixation times and network properties.

  8. Principles of ex ovo competitive exclusion and in ovo administration of Lactobacillus reuteri.

    PubMed

    Edens, F W; Parkhurst, C R; Casas, I A; Dobrogosz, W J

    1997-01-01

    The data that have been presented indicate that the in ovo use of competitive exclusion (CE) agents is feasible for both chickens and turkeys. However, there are many pitfalls that await the use of in ovo application of CE agents, including the use of nonspecies-specific intestinal microbes and the use of harmful proteolytic, gas-producing and toxin-producing intestinal microbes. Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in having a prolonged effect in the hatched chick or poult. Lactobacillus reuteri administration in ovo increases its rate of intestinal colonization and decreases the colonization of Salmonella and Escherichia coli in both chicks and poults. Additionally, mortality due to in-hatcher exposure to E. coli or Salmonella is reduced with in ovo L. reuteri. Use of antibiotics in ovo may preclude the use of co-administered CE agents, but Gentamicin and L. reuteri are a compatible mixture when administered in ovo in separate compartments. Nevertheless, the intestinal morphology can be affected by both the CE agent and by antibiotics. Lactobacillus reuteri both in ovo and ex ovo will increase villus height and crypt depth, and Gentamicin in ovo causes a shortening and blunting of the villus. Both Gentamicin and L. reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiotic effects shortening and blunting of the intestinal villi does not correct itself. Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicin in ovo, and this is presumably due to the increase in potentially pathogenic bacteria in the intestinal tract. Diminishing antibiotic effects posthatch would then negatively affect the absorption of nutrients and reduce growth at least in a transitory manner. Thus, L reuteri administration in ovo singly or in combination with Gentamicin followed by L

  9. Effect of porcine-derived mucosal competitive exclusion culture on antimicrobial resistance in Escherichia coli from growing piglets.

    PubMed

    Kim, L M; Gray, Jeffery T; Bailey, J Stan; Jones, Richard D; Fedorka-Cray, Paula J

    2005-01-01

    While use of antimicrobial drugs in livestock production has made a significant impact on animal health, welfare, and productivity, interest in suitable alternatives such as pre/probiotics, organic acids, and cultures of normal flora or "competitive exclusion" cultures from young animals has increased significantly in the wake of the antimicrobial resistance issue. The present study was undertaken to determine the effect of porcine-derived mucosal competitive exclusion (PCE) culture on both the antimicrobial susceptibility of commensal E. coli and on growth performance in piglets. Two replicate trials were conducted using growing piglets fed standard antimicrobial-free production diets. Piglets in the treatment group were orally dosed with PCE (10(10) cfu/mL) twice within 24 h of birth, at weaning, and 18-24 h post-weaning; control group piglets were dosed with sterile broth as a placebo. Fecal samples from all piglets were cultured for commensal E. coli at dosing times and when feed type was changed. A significantly higher proportion of E. coli from PCE-treated piglets demonstrated resistance to tetracycline (p < 0.0001), and streptomycin (p < 0.0001) when compared to controls. Resistance to streptomycin resistance in E. coli from piglets treated with PCE culture was variable, returning to baseline levels by day 21 (weaning). Piglets treated with the PCE culture demonstrated improved feed efficiencies when compared to control piglets (p < 0.005) during feeding of the starter and first growth diets. The PCE culture used in the present study had previously been shown to effectively exclude Salmonella in pigs. To the best of the authors' knowledge, this is the first report characterizing the effect of a competitive exclusion culture on antimicrobial resistance of commensal E. coli.

  10. Follow-on biologics: data exclusivity and the balance between innovation and competition.

    PubMed

    Grabowski, Henry

    2008-06-01

    Legislation to create a regulatory pathway for follow-on biologics is currently being considered by the United States Congress. A critical issue in this respect is the period of data exclusivity for innovator companies before a follow-on competitor can rely in part on data obtained for an original biologic for an abbreviated approval. Given the nature of patents on biologics, the period of data exclusivity is anticipated to have a key role in determining how quickly follow-on competitors emerge, and consequently also on the time available for originator companies to recoup their investment. With this issue in mind, this article discusses factors influencing return on investment on biologic research and development. A break-even analysis for a representative portfolio of biologics provides support for a substantial data exclusivity period.

  11. Theoretical convergence guarantees for cooperative coevolutionary algorithms.

    PubMed

    Panait, Liviu

    2010-01-01

    Cooperative coevolutionary algorithms have the potential to significantly speed up the search process by dividing the space into parts that can each be conquered separately. However, recent research presented theoretical and empirical arguments that these algorithms tend to converge to suboptimal solutions in the search space, and are thus not fit for optimization tasks. This paper details an extended formal model for cooperative coevolutionary algorithms, and uses it to explore possible reasons these algorithms converge to optimal or suboptimal solutions. We demonstrate that, under specific conditions, this theoretical model will converge to the globally optimal solution. The proofs provide the underlying theoretical foundation for a better application of cooperative coevolutionary algorithms. We demonstrate the practical advantages of applying ideas from this theoretical work to a simple problem domain.

  12. The mechanism for exclusion of Pinus massoniana during the succession in subtropical forest ecosystems: light competition or stoichiometric homoeostasis?

    PubMed

    Yan, Junhua; Li, Kun; Peng, Xingju; Huang, Zhongliang; Liu, Shizhong; Zhang, Qianmei

    2015-06-05

    Competition for light has traditionally been considered as the main mechanism for exclusion of Pinus massoniana during succession in subtropical forest ecosystems. However, both long-term inventories and a seedling cultivation experiment showed that growth of mature individuals and young seedlings of P. massoniana was not limited by available light, but was strongly influenced by stoichiometric homoeostasis. This is supported by the results of homoeostatic regulation coefficients for nitrogen (HN) and phosphorus (HP) estimated using the measured data from six transitional forests across subtropical China. Among three dominant tree species in subtropical forests, P. massoniana and Castanopsis chinensis had the lowest values of HP and HN, respectively. Therefore P. massoniana cannot survive in the advanced stage due to soil phosphorus limitation and C. chinensis cannot successfully grow in the pioneer stage due to soil nitrogen limitation. Our results support that stoichiometric homeostasis is the main reason for gradual exclusion of P. massoniana from the transitional forest and the eventual elimination from the advanced forest during the subtropical forest succession. Therefore greater attention should be paid to stoichiometric homeostasis as one of the key mechanisms for species exclusion during forest succession.

  13. The mechanism for exclusion of Pinus massoniana during the succession in subtropical forest ecosystems: light competition or stoichiometric homoeostasis?

    PubMed Central

    Yan, Junhua; Li, Kun; Peng, Xingju; Huang, Zhongliang; Liu, Shizhong; Zhang, Qianmei

    2015-01-01

    Competition for light has traditionally been considered as the main mechanism for exclusion of Pinus massoniana during succession in subtropical forest ecosystems. However, both long-term inventories and a seedling cultivation experiment showed that growth of mature individuals and young seedlings of P. massoniana was not limited by available light, but was strongly influenced by stoichiometric homoeostasis. This is supported by the results of homoeostatic regulation coefficients for nitrogen (HN) and phosphorus (HP) estimated using the measured data from six transitional forests across subtropical China. Among three dominant tree species in subtropical forests, P. massoniana and Castanopsis chinensis had the lowest values of HP and HN, respectively. Therefore P. massoniana cannot survive in the advanced stage due to soil phosphorus limitation and C. chinensis cannot successfully grow in the pioneer stage due to soil nitrogen limitation. Our results support that stoichiometric homeostasis is the main reason for gradual exclusion of P. massoniana from the transitional forest and the eventual elimination from the advanced forest during the subtropical forest succession. Therefore greater attention should be paid to stoichiometric homeostasis as one of the key mechanisms for species exclusion during forest succession. PMID:26046944

  14. Seasonal sexual segregation in two Thalassarche albatross species: competitive exclusion, reproductive role specialization or foraging niche divergence?

    PubMed Central

    Phillips, R. A.; Silk, J. R. D.; Phalan, B.; Catry, P.; Croxall, J. P.

    2004-01-01

    Sexual segregation by micro- or macrohabitat is common in birds, and usually attributed to size-mediated dominance and exclusion of females by larger males, trophic niche divergence or reproductive role specialization. Our study of black-browed albatrosses, Thalassarche melanophrys, and grey-headed albatrosses, T. chrysostoma, revealed an exceptional degree of sexual segregation during incubation, with largely mutually exclusive core foraging ranges for each sex in both species. Spatial segregation was not apparent during brood-guard or post-guard chick rearing, when adults are constrained to feed close to colonies, providing no evidence for dominance-related competitive exclusion at the macrohabitat level. A comprehensive morphometric comparison indicated considerable species and sexual dimorphism in wing area and wing loading that corresponded, both within and between species, to broad-scale habitat preferences relating to wind strength. We suggest that seasonal sexual segregation in these two species is attributable to niche divergence mediated by differences in flight performance. Such sexual segregation may also have implications for conservation in relation to sex-specific overlap with commercial fisheries. PMID:15306353

  15. Seasonal sexual segregation in two Thalassarche albatross species: competitive exclusion, reproductive role specialization or foraging niche divergence?

    PubMed

    Phillips, R A; Silk, J R D; Phalan, B; Catry, P; Croxall, J P

    2004-06-22

    Sexual segregation by micro- or macrohabitat is common in birds, and usually attributed to size-mediated dominance and exclusion of females by larger males, trophic niche divergence or reproductive role specialization. Our study of black-browed albatrosses, Thalassarche melanophrys, and grey-headed albatrosses, T. chrysostoma, revealed an exceptional degree of sexual segregation during incubation, with largely mutually exclusive core foraging ranges for each sex in both species. Spatial segregation was not apparent during brood-guard or post-guard chick rearing, when adults are constrained to feed close to colonies, providing no evidence for dominance-related competitive exclusion at the macrohabitat level. A comprehensive morphometric comparison indicated considerable species and sexual dimorphism in wing area and wing loading that corresponded, both within and between species, to broad-scale habitat preferences relating to wind strength. We suggest that seasonal sexual segregation in these two species is attributable to niche divergence mediated by differences in flight performance. Such sexual segregation may also have implications for conservation in relation to sex-specific overlap with commercial fisheries.

  16. Exclusion and spatial segregation in the apparent competition between two hosts sharing macroparasites.

    PubMed

    Manica, Mattia; Rosà, Roberto; Pugliese, Andrea; Bolzoni, Luca

    2013-06-01

    In this paper we investigate the spatial dynamics of a deterministic model describing two host species that partially share a common spatial domain, experiencing apparent competition mediated by macroparasites. The aim of this work is to understand the mechanisms underlying apparent competition processes in a spatially structured environment, which have been generally overlooked up to now. First, we analyse the behaviour of a single-host macroparasite partial differential equation (PDE) model, both in the cases of uniform or spatially-dependent vital rates of the host, focusing on the role of spatial diffusion on parasite persistence and host abundance. We obtained the threshold condition for parasite persistence, and (in contrast to what occurs in reaction-diffusion models for an isolated population) we found that, in the case of spatially-dependent vital rates, increasing the host diffusion coefficient results in an increase of the overall host population. Then, a PDE model featuring spatial diffusion and apparent competition mediated via shared macroparasites between two species is analysed in order to understand the role of spatial heterogeneity in host coexistence. We assumed a partial overlap among the habitats of the two species and found that the shared parasites could cause, depending on the values of the diffusion coefficients and differences in induced mortality among host species, a decrease of the realized habitat and, eventually, the extinction of the species less tolerant to parasite infection. This shows that the presence of regulating parasites complicates the effect of dispersal on population dynamics and that the dynamics of apparent competition cannot be adequately understood from spatially-independent models.

  17. Competition between multiple totally asymmetric simple exclusion processes for a finite pool of resources

    NASA Astrophysics Data System (ADS)

    Cook, L. Jonathan; Zia, R. K. P.; Schmittmann, B.

    2009-09-01

    Using Monte Carlo simulations and a domain-wall theory, we discuss the effect of coupling several totally asymmetric simple exclusion processes (TASEPs) to a finite reservoir of particles. This simple model mimics directed biological transport processes in the presence of finite resources such as protein synthesis limited by a finite pool of ribosomes. If all TASEPs have equal length, we find behavior which is analogous to a single TASEP coupled to a finite pool. For the more generic case of chains with different lengths, several unanticipated regimes emerge. A generalized domain-wall theory captures our findings in good agreement with simulation results.

  18. Comparing a Coevolutionary Genetic Algorithm for Multiobjective Optimization

    NASA Technical Reports Server (NTRS)

    Lohn, Jason D.; Kraus, William F.; Haith, Gary L.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    We present results from a study comparing a recently developed coevolutionary genetic algorithm (CGA) against a set of evolutionary algorithms using a suite of multiobjective optimization benchmarks. The CGA embodies competitive coevolution and employs a simple, straightforward target population representation and fitness calculation based on developmental theory of learning. Because of these properties, setting up the additional population is trivial making implementation no more difficult than using a standard GA. Empirical results using a suite of two-objective test functions indicate that this CGA performs well at finding solutions on convex, nonconvex, discrete, and deceptive Pareto-optimal fronts, while giving respectable results on a nonuniform optimization. On a multimodal Pareto front, the CGA finds a solution that dominates solutions produced by eight other algorithms, yet the CGA has poor coverage across the Pareto front.

  19. The impact of predation on the coexistence and competitive exclusion of pathogens in prey.

    PubMed

    Lv, Yunfei; Yuan, Rong; Pei, Yongzhen

    2014-05-01

    A two-strain epidemic model with saturating contact rate under a generalist predator is proposed. For a generalist predator which feeds on many types of prey, we assume that the predator can discriminate among susceptible and infected with each strain prey. First, mathematical analysis of the model with regard to invariance of nonnegativity, boundedness of solutions, nature of equilibria, persistence and global stability are analyzed. Second, the two strains will competitively exclude each other in the absence of predation with the strain with the larger reproduction number persisting. If predation is discriminate, then depending on the predation level, a dominant strain may occur. Thus, for some predation levels, the strain one may persist while for other predation levels strain two may persist. Furthermore, coexistence line and coexistent asymptotic-periodic solution are obtained when coexistence occur while heteroclinic is obtained when the two strains competitively exclude each other. Finally, the impact of predation is mentioned along with numerical results to provide some support to the analytical findings.

  20. Frequency-dependent assistance as a way out of competitive exclusion between two strains of an emerging virus

    PubMed Central

    Péréfarres, Frédéric; Thébaud, Gaël; Lefeuvre, Pierre; Chiroleu, Frédéric; Rimbaud, Loup; Hoareau, Murielle; Reynaud, Bernard; Lett, Jean-Michel

    2014-01-01

    Biological invasions are the main causes of emerging viral diseases and they favour the co-occurrence of multiple species or strains in the same environment. Depending on the nature of the interaction, co-occurrence can lead to competitive exclusion or coexistence. The successive fortuitous introductions of two strains of Tomato yellow leaf curl virus (TYLCV-Mld and TYLCV-IL) in Réunion Island provided an ideal opportunity to study the invasion of, and competition between, these worldwide emerging pathogens. During a 7-year field survey, we observed a displacement of the resident TYLCV-Mld by the newcomer TYLCV-IL, with TYLCV-Mld remaining mostly in co-infected plants. To understand the factors associated with this partial displacement, biological traits related to fitness were measured. The better ecological aptitude of TYLCV-IL in single infections was demonstrated, which explains its rapid spread. However, we demonstrate that the relative fitness of virus strains can drastically change between single infections and co-infections. An epidemiological model parametrized with our experimental data predicts that the two strains will coexist in the long run through assistance by the fitter strain. This rare case of unilateral facilitation between two pathogens leads to frequency-dependent selection and maintenance of the less fit strain. PMID:24598426

  1. Frequency-dependent assistance as a way out of competitive exclusion between two strains of an emerging virus.

    PubMed

    Péréfarres, Frédéric; Thébaud, Gaël; Lefeuvre, Pierre; Chiroleu, Frédéric; Rimbaud, Loup; Hoareau, Murielle; Reynaud, Bernard; Lett, Jean-Michel

    2014-04-22

    Biological invasions are the main causes of emerging viral diseases and they favour the co-occurrence of multiple species or strains in the same environment. Depending on the nature of the interaction, co-occurrence can lead to competitive exclusion or coexistence. The successive fortuitous introductions of two strains of Tomato yellow leaf curl virus (TYLCV-Mld and TYLCV-IL) in Réunion Island provided an ideal opportunity to study the invasion of, and competition between, these worldwide emerging pathogens. During a 7-year field survey, we observed a displacement of the resident TYLCV-Mld by the newcomer TYLCV-IL, with TYLCV-Mld remaining mostly in co-infected plants. To understand the factors associated with this partial displacement, biological traits related to fitness were measured. The better ecological aptitude of TYLCV-IL in single infections was demonstrated, which explains its rapid spread. However, we demonstrate that the relative fitness of virus strains can drastically change between single infections and co-infections. An epidemiological model parametrized with our experimental data predicts that the two strains will coexist in the long run through assistance by the fitter strain. This rare case of unilateral facilitation between two pathogens leads to frequency-dependent selection and maintenance of the less fit strain.

  2. Kind discrimination and competitive exclusion mediated by contact-dependent growth inhibition systems shape biofilm community structure.

    PubMed

    Anderson, Melissa S; Garcia, Erin C; Cotter, Peggy A

    2014-04-01

    Contact-Dependent Growth Inhibition (CDI) is a phenomenon in which bacteria use the toxic C-terminus of a large exoprotein (called BcpA in Burkholderia species) to inhibit the growth of neighboring bacteria upon cell-cell contact. CDI systems are present in a wide range of Gram-negative proteobacteria and a hallmark feature is polymorphism amongst the exoprotein C-termini (BcpA-CT in Burkholderia) and amongst the small immunity proteins (BcpI) that protect against CDI in an allele-specific manner. In addition to CDI, the BcpAIOB proteins of Burkholderia thailandensis mediate biofilm formation, and they do so independent of BcpA-mediated interbacterial competition, suggesting a cooperative role for CDI system proteins in this process. CDI has previously only been demonstrated between CDI+ and CDI- bacteria, leaving the roles of CDI system-mediated interbacterial competition and of CDI system diversity in nature unknown. We constructed B. thailandensis strains that differed only in the BcpA-CT and BcpI proteins they produced. When co-cultured on agar, these strains each participated in CDI and the outcome of the competition depended on both CDI system efficiency and relative bacterial numbers initially. Strains also participated in CDI during biofilm development, resulting in pillar structures that were composed of only a single BcpA-CT/BcpI type. Moreover, a strain producing BcpA-CT/BcpI proteins of one type was prevented from joining a pre-established biofilm community composed of bacteria producing BcpA-CT/BcpI proteins of a different type, unless it also produced the BcpI protein of the established strain. Bacteria can therefore use CDI systems for kind recognition and competitive exclusion of 'non-self' bacteria from a pre-established biofilm. Our data indicate that CDI systems function in both cooperative and competitive behaviors to build microbial communities that are composed of only bacteria that are related via their CDI system alleles.

  3. Host Gut Motility Promotes Competitive Exclusion within a Model Intestinal Microbiota

    PubMed Central

    Baker, Ryan P; Schlomann, Brandon H; Ganz, Julia; Eisen, Judith S; Guillemin, Karen; Parthasarathy, Raghuveer

    2016-01-01

    The gut microbiota is a complex consortium of microorganisms with the ability to influence important aspects of host health and development. Harnessing this “microbial organ” for biomedical applications requires clarifying the degree to which host and bacterial factors act alone or in combination to govern the stability of specific lineages. To address this issue, we combined bacteriological manipulation and light sheet fluorescence microscopy to monitor the dynamics of a defined two-species microbiota within a vertebrate gut. We observed that the interplay between each population and the gut environment produces distinct spatiotemporal patterns. As a consequence, one species dominates while the other experiences sudden drops in abundance that are well fit by a stochastic mathematical model. Modeling revealed that direct bacterial competition could only partially explain the observed phenomena, suggesting that a host factor is also important in shaping the community. We hypothesized the host determinant to be gut motility, and tested this mechanism by measuring colonization in hosts with enteric nervous system dysfunction due to a mutation in the ret locus, which in humans is associated with the intestinal motility disorder known as Hirschsprung disease. In mutant hosts we found reduced gut motility and, confirming our hypothesis, robust coexistence of both bacterial species. This study provides evidence that host-mediated spatial structuring and stochastic perturbation of communities can drive bacterial population dynamics within the gut, and it reveals a new facet of the intestinal host–microbe interface by demonstrating the capacity of the enteric nervous system to influence the microbiota. Ultimately, these findings suggest that therapeutic strategies targeting the intestinal ecosystem should consider the dynamic physical nature of the gut environment. PMID:27458727

  4. Competitive exclusion among fig wasps achieved via entrainment of host plant flowering phenology.

    PubMed

    Liu, Min; Zhao, Rui; Chen, Yan; Zhang, Jian; Compton, Stephen G; Chen, Xiao-Yong

    2014-01-01

    Molecular techniques are revealing increasing numbers of morphologically similar but co-existing cryptic species, challenging the niche theory. To understand the co-existence mechanism, we studied phenologies of morphologically similar species of fig wasps that pollinate the creeping fig (F. pumila) in eastern China. We compared phenologies of fig wasp emergence and host flowering at sites where one or both pollinators were present. At the site where both pollinators were present, we used sticky traps to capture the emerged fig wasps and identified species identity using mitochondrial DNA COI gene. We also genotyped F. pumila individuals of the three sites using polymorphic microsatellites to detect whether the host populations were differentiated. Male F. pumila produced two major crops annually, with figs receptive in spring and summer. A small partial third crop of receptive figs occurred in the autumn, but few of the second crop figs matured at that time. Hence, few pollinators were available to enter third crop figs and they mostly aborted, resulting in two generations of pollinating wasps each year, plus a partial third generation. Receptive figs were produced on male plants in spring and summer, timed to coincide with the release of short-lived adult pollinators from the same individual plants. Most plants were pollinated by a single species. Plants pollinated by Wiebesia sp. 1 released wasps earlier than those pollinated by Wiebesia sp. 3, with little overlap. Plants occupied by different pollinators were not spatially separated, nor genetically distinct. Our findings show that these differences created mismatches with the flight periods of the other Wiebesia species, largely 'reserving' individual plants for the resident pollinator species. This pre-emptive competitive displacement may prevent long term co-existence of the two pollinators.

  5. Competitive Exclusion among Fig Wasps Achieved via Entrainment of Host Plant Flowering Phenology

    PubMed Central

    Chen, Yan; Zhang, Jian; Compton, Stephen G.; Chen, Xiao-Yong

    2014-01-01

    Molecular techniques are revealing increasing numbers of morphologically similar but co-existing cryptic species, challenging the niche theory. To understand the co-existence mechanism, we studied phenologies of morphologically similar species of fig wasps that pollinate the creeping fig (F. pumila) in eastern China. We compared phenologies of fig wasp emergence and host flowering at sites where one or both pollinators were present. At the site where both pollinators were present, we used sticky traps to capture the emerged fig wasps and identified species identity using mitochondrial DNA COI gene. We also genotyped F. pumila individuals of the three sites using polymorphic microsatellites to detect whether the host populations were differentiated. Male F. pumila produced two major crops annually, with figs receptive in spring and summer. A small partial third crop of receptive figs occurred in the autumn, but few of the second crop figs matured at that time. Hence, few pollinators were available to enter third crop figs and they mostly aborted, resulting in two generations of pollinating wasps each year, plus a partial third generation. Receptive figs were produced on male plants in spring and summer, timed to coincide with the release of short-lived adult pollinators from the same individual plants. Most plants were pollinated by a single species. Plants pollinated by Wiebesia sp. 1 released wasps earlier than those pollinated by Wiebesia sp. 3, with little overlap. Plants occupied by different pollinators were not spatially separated, nor genetically distinct. Our findings show that these differences created mismatches with the flight periods of the other Wiebesia species, largely ‘reserving’ individual plants for the resident pollinator species. This pre-emptive competitive displacement may prevent long term co-existence of the two pollinators. PMID:24849458

  6. Competitive Exclusion Reduces Transmission and Excretion of Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Broilers.

    PubMed

    Ceccarelli, Daniela; van Essen-Zandbergen, Alieda; Smid, Bregtje; Veldman, Kees T; Boender, Gert Jan; Fischer, Egil A J; Mevius, Dik J; van der Goot, Jeanet A

    2017-06-01

    Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (pAmpC) are enzymes able to hydrolyze a large variety of β-lactam antibiotics, including third-generation cephalosporins and monobactams. Broilers and broiler meat products can be highly contaminated with ESBL- and pAmpC-producing Escherichia coli strains, also known as extended-spectrum cephalosporin (ESC)-resistant E. coli strains, and can be a source for human infections. As few data on interventions to reduce the presence of ESC-resistant E. coli in broilers are available, we used transmission experiments to examine the role of competitive exclusion (CE) on reducing transmission and excretion in broilers. A broiler model to study the transmission of ESC-resistant E. coli was set up. Day-old chickens were challenged with an ESBL-producing E. coli strain isolated from healthy broilers in the Netherlands. Challenged and not challenged chicks were housed together in pairs or in groups, and ESBL-producing E. coli transmission was monitored via selective culturing of cloacal swab specimens. We observed a statistically significant reduction in both the transmission and excretion of ESBL-producing E. coli in chicks treated with the probiotic flora before E. coli challenge compared to the transmission and excretion in untreated controls. In conclusion, our results support the use of competitive exclusion as an intervention strategy to control ESC-resistant E. coli in the field.IMPORTANCE Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases are a primary cause of resistance to β-lactam antibiotics among members of the family Enterobacteriaceae in humans, animals, and the environment. Food-producing animals are not exempt from this, with a high prevalence being seen in broilers, and there is evidence pointing to a possible foodborne source for human contamination. We investigated the effect of administration of a commercial probiotic product as an intervention to

  7. The structure of a furin-antibody complex explains non-competitive inhibition by steric exclusion of substrate conformers.

    PubMed

    Dahms, Sven O; Creemers, John W M; Schaub, Yvonne; Bourenkov, Gleb P; Zögg, Thomas; Brandstetter, Hans; Than, Manuel E

    2016-09-27

    Proprotein Convertases (PCs) represent highly selective serine proteases that activate their substrates upon proteolytic cleavage. Their inhibition is a promising strategy for the treatment of cancer and infectious diseases. Inhibitory camelid antibodies were developed, targeting the prototypical PC furin. Kinetic analyses of them revealed an enigmatic non-competitive mechanism, affecting the inhibition of large proprotein-like but not small peptidic substrates. Here we present the crystal structures of furin in complex with the antibody Nb14 and of free Nb14 at resolutions of 2.0 Å and 2.3 Å, respectively. Nb14 binds at a site distant to the substrate binding pocket to the P-domain of furin. Interestingly, no major conformational changes were observed upon complex formation, neither for the protease nor for the antibody. Inhibition of furin by Nb14 is instead explained by steric exclusion of specific substrate conformers, explaining why Nb14 inhibits the processing of bulky protein substrates but not of small peptide substrates. This mode of action was further supported by modelling studies with the ternary factor X-furin-antibody complex and a mutation that disrupted the interaction interface between furin and the antibody. The observed binding mode of Nb14 suggests a novel approach for the development of highly specific antibody-based proprotein convertase inhibitors.

  8. The structure of a furin-antibody complex explains non-competitive inhibition by steric exclusion of substrate conformers

    PubMed Central

    Dahms, Sven O.; Creemers, John W. M.; Schaub, Yvonne; Bourenkov, Gleb P.; Zögg, Thomas; Brandstetter, Hans; Than, Manuel E.

    2016-01-01

    Proprotein Convertases (PCs) represent highly selective serine proteases that activate their substrates upon proteolytic cleavage. Their inhibition is a promising strategy for the treatment of cancer and infectious diseases. Inhibitory camelid antibodies were developed, targeting the prototypical PC furin. Kinetic analyses of them revealed an enigmatic non-competitive mechanism, affecting the inhibition of large proprotein-like but not small peptidic substrates. Here we present the crystal structures of furin in complex with the antibody Nb14 and of free Nb14 at resolutions of 2.0 Å and 2.3 Å, respectively. Nb14 binds at a site distant to the substrate binding pocket to the P-domain of furin. Interestingly, no major conformational changes were observed upon complex formation, neither for the protease nor for the antibody. Inhibition of furin by Nb14 is instead explained by steric exclusion of specific substrate conformers, explaining why Nb14 inhibits the processing of bulky protein substrates but not of small peptide substrates. This mode of action was further supported by modelling studies with the ternary factor X-furin-antibody complex and a mutation that disrupted the interaction interface between furin and the antibody. The observed binding mode of Nb14 suggests a novel approach for the development of highly specific antibody-based proprotein convertase inhibitors. PMID:27670069

  9. Competitive exclusion of a worldwide invasive pest by a native. Quantifying competition between two phytophagous insects on two host plant species.

    PubMed

    Paini, Dean R; Funderburk, Joe E; Reitz, Stuart R

    2008-01-01

    1. High competitive ability is believed to be an important characteristic of invasive species. Many animal studies have compared the competitive ability of invasive species with a native species that is being displaced, but few have looked at systems where an invasive species has failed to establish itself. These types of studies are important to determine if competition is relevant not only to invading species but also to the biotic resistance of a community. 2. The thrips species F. occidentalis is a highly invasive pest that has spread from its original range (the western states of the USA) to a worldwide distribution. Despite this, F. occidentalis is largely absent or occurs in low numbers in the eastern states of the USA, where the native F. tritici dominates. It is possible that F. tritici is competitively excluding F. occidentalis from this region. 3. Larval competition between these two thrips species was tested on two known plant hosts, Capsicum annuum (a crop plant), and Raphanus raphanistrum (an invasive weed), using a response surface design with number of larvae surviving as the response variable. The response surface design allowed competition models to be fit to data using maximum likelihood estimation, thus generating quantitative values for interspecific competition. 4. On both plant hosts, the native F. tritici did not experience significant interspecific competition from the invasive F. occidentalis. In contrast, F. occidentalis did experience significant interspecific competition from F. tritici. Competition from F. tritici larvae on F. occidentalis larvae was estimated to be 1.72 times (on C. annuum) and 1.76 times (on R. raphanistrum) the effect of intraspecific competition. The invasive F. occidentalis appears to be competitively excluded by the native F. tritici. 5. This study confirms the importance of competition in the biotic resistance of a community and is one of the few animal studies to not only test for competition in an apparently

  10. Coevolutionary dynamics with clustering behaviors on cyclic competition

    NASA Astrophysics Data System (ADS)

    Dong, Linrong; Yang, Guangcan

    2012-05-01

    We propose a dynamic model for describing clustering behaviors on a cyclic game, in which the same species form a cluster to compete. The rates of consuming the prey depend not only on the individual competing ability v, but also on the two interacting cluster’s sizes. The fragmentation and coagulation rates of the clusters are related to the cohesive strength among the individuals. A new parameter u is introduced to indicate the uniting degree. We find that the probability distribution of the clustering sizes is almost a power law in a large regime specified by the two parameters, which reflects the scale-free behavior in complex systems. In addition, the exponential magnitudes are mostly in the range of real social systems. Our simulation shows that clustering promotes biodiversity. At steady state, the amounts about the three species evolve tempestuously with asymmetric period; the aggregations about big size’s clusters to compete are obvious and on-off intermittence.

  11. A field test for competitive effects of Aedes albopictus on A. aegypti in South Florida: differences between sites of coexistence and exclusion?

    PubMed Central

    Juliano, Steven A.; Lounibos, L. Philip; O’Meara, George F.

    2007-01-01

    We tested whether interspecific competition from Aedes albopictus had measurable effects on A. aegypti at the typical numbers of larval mosquitoes found in cemetery vases in south Florida. We also tested whether the effect of interspecific competition from A. albopictus on A. aegypti differed between sites where A. aegypti either persists or went extinct following invasion by A. albopictus. Similar experiments manipulating numbers of A. albopictus in cemetery vases were conducted at three sites of A. aegypti persistence and three sites where A. aegypti was apparently extinct. The experiments were done using numbers of larvae that were determined by observed numbers of larvae for each site, and with resources (leaf detritus) that accumulated in experimental vases placed into each field site. In both the early rainy season (when number of mosquito larvae was low) and the late rainy season (when number of mosquito larvae was high), there was a significant effect of treatment on developmental progress of experimental A. aegypti. In the late rainy season, when numbers of larvae were high, there was also a significant effect of treatment on survivorship of A. aegypti. However, the competition treatment × site type (A. aegypti persists vs extinct) interaction was never significant, indicating that the competitive effect of A. albopictus on A. aegypti did not differ systematically between persistence versus extinction sites. Thus, although competition from A. albopictus is strong under field conditions at all sites, we find no evidence that variation in the impact of interspecific competition is associated with coexistence or exclusion. Interspecific competition among larvae is thus a viable explanation for exclusion or reduction of A. aegypti in south Florida, but variation in the persistence of A. aegypti following invasion does not seem to be primarily a product of variation in the conditions in the aquatic environments of cemetery vases. PMID:15024640

  12. Evolving Coevolutionary Classifiers Under Large Attribute Spaces

    NASA Astrophysics Data System (ADS)

    Doucette, John; Lichodzijewski, Peter; Heywood, Malcolm

    Model-building under the supervised learning domain potentially face a dual learning problem of identifying both the parameters of the model and the subset of (domain) attributes necessary to support the model, thus using an embedded as opposed to wrapper or filter based design. Genetic Programming (GP) has always addressed this dual problem, however, further implicit assumptions are made which potentially increase the complexity of the resulting solutions. In this work we are specifically interested in the case of classification under very large attribute spaces. As such it might be expected that multiple independent/ overlapping attribute subspaces support the mapping to class labels; whereas GP approaches to classification generally assume a single binary classifier per class, forcing the model to provide a solution in terms of a single attribute subspace and single mapping to class labels. Supporting the more general goal is considered as a requirement for identifying a 'team' of classifiers with non-overlapping classifier behaviors, in which each classifier responds to different subsets of exemplars. Moreover, the subsets of attributes associated with each team member might utilize a unique 'subspace' of attributes. This work investigates the utility of coevolutionary model building for the case of classification problems with attribute vectors consisting of 650 to 100,000 dimensions. The resulting team based coevolutionary evolutionary method-Symbiotic Bid-based (SBB) GP-is compared to alternative embedded classifier approaches of C4.5 and Maximum Entropy Classification (MaxEnt). SSB solutions demonstrate up to an order of magnitude lower attribute count relative to C4.5 and up to two orders of magnitude lower attribute count than MaxEnt while retaining comparable or better classification performance. Moreover, relative to the attribute count of individual models participating within a team, no more than six attributes are ever utilized; adding a further

  13. Competition.

    PubMed

    Chambers, D W

    1997-01-01

    Our ambivalence toward competition can be traced to an unspoken preference for certain types of competition which give us an advantage over the types we value less. Four types are defined (a) pure (same rules, same objectives), (b) collaborative (same rules, shared objective), (c) market share (different rules, same objectives), and (d) market growth (different rules, value added orientation). The defining characteristics of the four types of competition are respectively: needing a referee, arguing over the spoils, differentiation and substitutability, and customer focus. Dentistry has features of all four types of competition, thus making it difficult to have a meaningful discussion or frame a coherent policy on this topic.

  14. Control of Listeria spp. by Competitive-Exclusion Bacteria in Floor Drains of a Poultry Processing Plant

    PubMed Central

    Zhao, Tong; Podtburg, Teresa C.; Zhao, Ping; Schmidt, Bruce E.; Baker, David A.; Cords, Bruce; Doyle, Michael P.

    2006-01-01

    In previous studies workers determined that two lactic acid bacterium isolates, Lactococcus lactis subsp. lactis C-1-92 and Enterococcus durans 152 (competitive-exclusion bacteria [CE]), which were originally obtained from biofilms in floor drains, are bactericidal to Listeria monocytogenes or inhibit the growth of L. monocytogenes both in vitro and in biofilms at 4 to 37°C. We evaluated the efficacy of these isolates for reducing Listeria spp. contamination of floor drains of a plant in which fresh poultry is processed. Baseline assays revealed that the mean numbers of Listeria sp. cells in floor drains sampled on six different dates (at approximately biweekly intervals) were 7.5 log10 CFU/100 cm2 for drain 8, 4.9 log10 CFU/100 cm2 for drain 3, 4.4 log10 CFU/100 cm2 for drain 2, 4.1 log10 CFU/100 cm2 for drain 4, 3.7 log10 CFU/100 cm2 for drain 1, and 3.6 log10 CFU/100 cm2 for drain 6. The drains were then treated with 107 CE/ml in an enzyme-foam-based cleaning agent four times in 1 week and twice a week for the following 3 weeks. In samples collected 1 week after CE treatments were applied Listeria sp. cells were not detectable (samples were negative as determined by selective enrichment culture) for drains 4 and 6 (reductions of 4.1 and 3.6 log10 CFU/100 cm2, respectively), and the mean numbers of Listeria sp. cells were 3.7 log10 CFU/100 cm2 for drain 8 (a reduction of 3.8 log10 CFU/100 cm2), <1.7 log10 CFU/100 cm2 for drain 1 (detectable only by selective enrichment culture; a reduction of 3.3 log10 CFU/100 cm2), and 2.6 log10 CFU/100 cm2 for drain 3 (a reduction of 2.3 log10 CFU/100 cm2). However, the aerobic plate counts for samples collected from floor drains before, during, and after CE treatment remained approximately the same. The results indicate that application of the two CE can greatly reduce the number of Listeria sp. cells in floor drains at 3 to 26°C in a facility in which fresh poultry is processed. PMID:16672472

  15. Organizational coevolutionary classifiers with fuzzy logic used in intrusion detection

    NASA Astrophysics Data System (ADS)

    Chen, Zhenguo

    2009-07-01

    Intrusion detection is an important technique in the defense-in-depth network security framework and a hot topic in computer security in recent years. To solve the intrusion detection question, we introduce the fuzzy logic into Organization CoEvolutionary algorithm [1] and present the algorithm of Organization CoEvolutionary Classification with Fuzzy Logic. In this paper, we give an intrusion detection models based on Organization CoEvolutionary Classification with Fuzzy Logic. After illustrating our model with a representative dataset and applying it to the real-world network datasets KDD Cup 1999. The experimental result shown that the intrusion detection based on Organizational Coevolutionary Classifiers with Fuzzy Logic can give higher recognition accuracy than the general method.

  16. Coevolutionary networks of reinforcement-learning agents.

    PubMed

    Kianercy, Ardeshir; Galstyan, Aram

    2013-07-01

    This paper presents a model of network formation in repeated games where the players adapt their strategies and network ties simultaneously using a simple reinforcement-learning scheme. It is demonstrated that the coevolutionary dynamics of such systems can be described via coupled replicator equations. We provide a comprehensive analysis for three-player two-action games, which is the minimum system size with nontrivial structural dynamics. In particular, we characterize the Nash equilibria (NE) in such games and examine the local stability of the rest points corresponding to those equilibria. We also study general n-player networks via both simulations and analytical methods and find that, in the absence of exploration, the stable equilibria consist of star motifs as the main building blocks of the network. Furthermore, in all stable equilibria the agents play pure strategies, even when the game allows mixed NE. Finally, we study the impact of exploration on learning outcomes and observe that there is a critical exploration rate above which the symmetric and uniformly connected network topology becomes stable.

  17. Coevolutionary networks of reinforcement-learning agents

    NASA Astrophysics Data System (ADS)

    Kianercy, Ardeshir; Galstyan, Aram

    2013-07-01

    This paper presents a model of network formation in repeated games where the players adapt their strategies and network ties simultaneously using a simple reinforcement-learning scheme. It is demonstrated that the coevolutionary dynamics of such systems can be described via coupled replicator equations. We provide a comprehensive analysis for three-player two-action games, which is the minimum system size with nontrivial structural dynamics. In particular, we characterize the Nash equilibria (NE) in such games and examine the local stability of the rest points corresponding to those equilibria. We also study general n-player networks via both simulations and analytical methods and find that, in the absence of exploration, the stable equilibria consist of star motifs as the main building blocks of the network. Furthermore, in all stable equilibria the agents play pure strategies, even when the game allows mixed NE. Finally, we study the impact of exploration on learning outcomes and observe that there is a critical exploration rate above which the symmetric and uniformly connected network topology becomes stable.

  18. Public goods games on adaptive coevolutionary networks

    NASA Astrophysics Data System (ADS)

    Pichler, Elgar; Shapiro, Avi M.

    2017-07-01

    Productive societies feature high levels of cooperation and strong connections between individuals. Public Goods Games (PGGs) are frequently used to study the development of social connections and cooperative behavior in model societies. In such games, contributions to the public good are made only by cooperators, while all players, including defectors, reap public goods benefits, which are shares of the contributions amplified by a synergy factor. Classic results of game theory show that mutual defection, as opposed to cooperation, is the Nash Equilibrium of PGGs in well-mixed populations, where each player interacts with all others. In this paper, we explore the coevolutionary dynamics of a low information public goods game on a complex network in which players adapt to their environment in order to increase individual payoffs relative to past payoffs parameterized by greediness. Players adapt by changing their strategies, either to cooperate or to defect, and by altering their social connections. We find that even if players do not know other players' strategies and connectivity, cooperation can arise and persist despite large short-term fluctuations.

  19. Competitiveness

    NASA Astrophysics Data System (ADS)

    Minihan, Charles E.

    1991-03-01

    Competition is defined as a spirited, sometimes ruthless, engagement of rivals such as in a race, a match, or an effort by one person to sell goods or services to customers in the marketplace of another. Sound familiar? If you will bear with me for a few minutes, I would like to examine competitiveness on a more global basis with emphasis on the rules of the game. You may be thinking that more often than not the competitive arena is relatively small and far from global, and its consequences are singularly influential on a trivial document called the P & L. However, with the newly established freedom of a major segment of the world population and with the industrial capability formerly known as Communist moving into what has heretofore been "our" limited arena, the competition could get very brisk. Brisk, and perhaps ruthless, unless we work together to try to establish an international industrial policy that is truly based on equality of competitive opportunity for all.

  20. Protein sites with more coevolutionary connections tend to evolve slower, while more variable protein families acquire higher coevolutionary connections.

    PubMed

    Mandloi, Sapan; Chakrabarti, Saikat

    2017-01-01

    Background: Amino acid exchanges within proteins sometimes compensate for one another and could therefore be co-evolved. It is essential to investigate the intricate relationship between the extent of coevolution and the evolutionary variability exerted at individual protein sites, as well as the whole protein. Methods: In this study, we have used a reliable set of coevolutionary connections (sites within 10Å spatial distance) and investigated their correlation with the evolutionary diversity within the respective protein sites. Results: Based on our observations, we propose an interesting hypothesis that higher numbers of coevolutionary connections are associated with lesser evolutionary variable protein sites, while higher numbers of the coevolutionary connections can be observed for a protein family that has higher evolutionary variability. Our findings also indicate that highly coevolved sites located in a solvent accessible state tend to be less evolutionary variable. This relationship reverts at the whole protein level where cytoplasmic and extracellular proteins show moderately higher anti-correlation between the number of coevolutionary connections and the average evolutionary conservation of the whole protein. Conclusions: Observations and hypothesis presented in this study provide intriguing insights towards understanding the critical relationship between coevolutionary and evolutionary changes observed within proteins. Our observations encourage further investigation to find out the reasons behind subtle variations in the relationship between coevolutionary connectivity and evolutionary diversity for proteins located at various cellular localizations and/or involved in different molecular-biological functions.

  1. A morphospace-based test for competitive exclusion among flying vertebrates: did birds, bats and pterosaurs get in each other's space?

    PubMed

    McGowan, A J; Dyke, G J

    2007-05-01

    Three vertebrate groups - birds, bats and pterosaurs - have evolved flapping flight over the past 200 million years. This innovation allowed each clade access to new ecological opportunities, but did the diversification of one of these groups inhibit the evolutionary radiation of any of the others? A related question is whether having the wing attached to the hindlimbs in bats and pterosaurs constrained their morphological diversity relative to birds. Fore- and hindlimb measurements from 894 specimens were used to construct a morphospace to assess morphological overlap and range, a possible indicator of competition, among the three clades. Neither birds nor bats entered pterosaur morphospace across the Cretaceous-Paleogene (Tertiary) extinction. Bats plot in a separate area from birds, and have a significantly smaller morphological range than either birds or pterosaurs. On the basis of these results, competitive exclusion among the three groups is not supported.

  2. Sympatric inhibition and niche differentiation suggest alternative coevolutionary trajectories among Streptomycetes.

    PubMed

    Kinkel, Linda L; Schlatter, Daniel C; Xiao, Kun; Baines, Anita D

    2014-02-01

    Soil bacteria produce a diverse array of antibiotics, yet our understanding of the specific roles of antibiotics in the ecological and evolutionary dynamics of microbial interactions in natural habitats remains limited. Here, we show a significant role for antibiotics in mediating antagonistic interactions and nutrient competition among locally coexisting Streptomycete populations from soil. We found that antibiotic inhibition is significantly more intense among sympatric than allopatric Streptomycete populations, indicating local selection for inhibitory phenotypes. For sympatric but not allopatric populations, antibiotic inhibition is significantly positively correlated with niche overlap, indicating that inhibition is targeted toward bacteria that pose the greatest competitive threat. Our results support the hypothesis that antibiotics serve as weapons in mediating local microbial interactions in soil and suggest that coevolutionary niche displacement may reduce the likelihood of an antibiotic arms race. Further insight into the diverse roles of antibiotics in microbial ecology and evolution has significant implications for understanding the persistence of antibiotic inhibitory and resistance phenotypes in environmental microbes, optimizing antibiotic drug discovery and developing strategies for managing microbial coevolutionary dynamics to enhance inhibitory phenotypes.

  3. Hybrid Co-Evolutionary Motion Planning via Visibility-Based Repair

    NASA Technical Reports Server (NTRS)

    Dozier, Gerry; McCullough, Shaun; Brown, Edward, Jr.; Homaifar, Abdollah; Bikdash, Mar-wan

    1997-01-01

    This paper introduces a hybrid co-evolutionary system for global motion planning within unstructured environments. This system combines the concept of co-evolutionary search along with a concept that we refer to as the visibility-based repair to form a hybrid which quickly transforms infeasible motions into feasible ones. Also, this system makes use of a novel representation scheme for the obstacles within an environment. Our hybrid evolutionary system differs from other evolutionary motion planners in that (1) more emphasis is placed on repairing infeasible motions to develop feasible motions rather than using simulated evolution exclusively as a means of discovering feasible motions, (2) a continuous map of the environment is used rather than a discretized map, and (3) it develops global motion plans for multiple mobile destinations by co-evolving populations of sub-global motion plans. In this paper, we demonstrate the effectiveness of this system by using it to solve two challenging motion planning problems where multiple targets try to move away from a point robot.

  4. Predation on pollinators promotes coevolutionary divergence in plant-pollinator mutualisms.

    PubMed

    Kagawa, Kotaro; Takimoto, Gaku

    2014-02-01

    Coevolution of plants and pollinators has been suggested as a mechanism driving diversification of plant-pollinator mutualisms. There is increasing recognition that predators or competitors can influence the abundance and behavior of pollinators and indirectly affect the fitness of plants. However, existing theories on plant-pollinator diversification focus exclusively on mutualistic interactions between plants and pollinators. Here we used simulations to evaluate whether predation on pollinators promotes coevolutionary diversification of plant-pollinator mutualisms. We developed an individual-based simulation model in which the blooming season of plants and the active seasons of pollinators and predators can evolve. In simulations without predators, plant-pollinator coevolution caused diversification in blooming/active seasons for both plants and pollinators, but this diversification resulted in polymorphisms, not speciation. The introduction of predators promoted a split of plant and pollinator populations into reproductively isolated subpopulations with corresponding blooming and active seasons or a directional shift of blooming and active seasons, increasing the possibility of plant-pollinator cospeciation. This result suggests that predation on pollinators can promote sympatric and allopatric divergence of plant-pollinator mutualisms. Joint action of antagonistic and mutualistic interactions may be fundamentally important for diversification in coevolutionary interactions.

  5. The efficacy of a commercial competitive exclusion product on Campylobacter colonization in broiler chickens in a 5-week pilot-scale study

    PubMed Central

    Schneitz, C.; Hakkinen, M.

    2016-01-01

    The efficacy of the commercial competitive exclusion product Broilact against Campylobacter jejuni was evaluated in broiler chickens in a 5-week pilot-scale study. Newly-hatched broiler chicks were brought from a commercial hatchery. After arrival 50 seeder chicks were challenged orally with approximately 103 cfu of C. jejuni, wing marked, and placed back in a delivery box and moved to a separate room. The rest of the chicks (contact chicks) were placed in floor pens, 100 chicks per pen. Birds in two pens were treated orally on the day of hatch with the commercial competitive exclusion (CE) product Broilact, and three pens were left untreated. The following day 10 seeder chicks were introduced into the Broilact treated and untreated control pens. One pen was left both untreated and unchallenged (0-control). Each week the ceca of 10 contact chicks and one seeder chick were examined quantitatively for Campylobacter. The treatment prevented or significantly reduced the colonization of the challenge organism in the ceca during the two first weeks; the percentage of colonized birds being 0% after the first week and 30% after the second week in the Broilact treated groups but was 100% in the control groups the entire 5-week rearing period. During the third rearing week the proportion of Campylobacter positive birds started to increase in the treated pens, being 80% after the third week and 95 and 90% after the fourth and fifth rearing weeks, respectively. Similarly the average count of Campylobacter in the cecal contents of the Broilact treated chicks started to increase, the difference between the treated and control chicks being 1.4 logs at the end of the rearing period. Although the protective effect was temporary and occurred only during the first two weeks of the rearing period, the results of this study support the earlier observations that CE flora designed to protect chicks from Salmonella may also reduce Campylobacter colonization of broiler chickens. PMID

  6. A restricted hybrid zone between native and introduced red fox (Vulpes vulpes) populations suggests reproductive barriers and competitive exclusion.

    PubMed

    Sacks, Benjamin N; Moore, Marcelle; Statham, Mark J; Wittmer, Heiko U

    2011-01-01

    Introduced species can threaten native taxa in multiple ways, including competition and hybridization, which can reduce fitness, alter ecological niches or swamp native genomes. Encroachment and hybridization by introduced species also provide opportunities to study the dynamics of invasiveness and hybridization during early stages following contact. We used 33 microsatellites, 51 single nucleotide polymorphisms and a mtDNA marker to characterize the extent and spatial pattern of encroachment and hybridization between a native, endemic subspecies of red fox (Vulpes vulpes patwin) and an introduced red fox population composed of highly admixed, phylogenetically divergent stock, resulting from a century of domestication. Both nuclear and mtDNA markers indicated that hybridization was primarily restricted to a narrow zone where the two populations came into contact. Although a few introgressed genotypes were detected in the interior of the native range, we found no immigrant foxes or F(1) or F(2) hybrids there, suggesting native foxes excluded introduced individuals. We speculate that the observed interbreeding at the periphery was facilitated by low densities. In total, 98% of mtDNA haplotypes in the native range were native and 96% of the nuclear ancestry was estimated to be native. Although the introduced range had expanded fivefold over the past four decades, native and non-native haplotypes from museum samples collected in and near the native range three decades earlier showed a similar geographic distribution as today, suggesting that the native range and hybrid zone were relatively stable. We hypothesize that the monogamous mating system of red foxes and other wild canids may enhance their resistance to hybridization because of greater fitness consequences associated with mate discrimination.

  7. Unique coevolutionary dynamics in a predator-prey system.

    PubMed

    Mougi, Akihiko; Iwasa, Yoh

    2011-05-21

    In this paper, we study the predator-prey coevolutionary dynamics when a prey's defense and a predator's offense change in an adaptive manner, either by genetic evolution or phenotypic plasticity, or by behavioral choice. Results are: (1) The coevolutionary dynamics are more likely to be stable if the predator adapts faster than the prey. (2) The prey population size can be nearly constant but the predator population can show very large amplitude fluctuations. (3) Both populations may oscillate in antiphase. All of these are not observed when the handling time is short and the prey's density dependence is weak. (4) The population dynamics and the trait dynamics show resonance: the amplitude of the population fluctuation is the largest when the speed of adaptation is intermediate. These results may explain experimental studies with microorganisms.

  8. Partner switching stabilizes cooperation in coevolutionary prisoner's dilemma

    NASA Astrophysics Data System (ADS)

    Fu, Feng; Wu, Te; Wang, Long

    2009-03-01

    Previous studies suggest that cooperation prevails when individuals can switch their interaction partners quickly. However, it is still unclear how quickly individuals should switch adverse partners to maximize cooperation. To address this issue, we propose a simple model of coevolutionary prisoner’s dilemma in which individuals are allowed to either adjust their strategies or switch their defective partners. Interestingly, we find that, depending on the game parameter, there is an optimal tendency of switching adverse partnerships that maximizes the fraction of cooperators in the population. We confirm that the stabilization of cooperation by partner switching remains effective under some situations, where either normalized or accumulated payoff is used in strategy updating, and where either only cooperators or all individuals are privileged to sever disadvantageous partners. We also provide an extended pair approximation to study the coevolutionary dynamics. Our results may be helpful in understanding the role of partner switching in the stabilization of cooperation in the real world.

  9. The efficacy of a commercial competitive exclusion product on Campylobacter colonization in broiler chickens in a 5-week pilot-scale study.

    PubMed

    Schneitz, C; Hakkinen, M

    2016-05-01

    The efficacy of the commercial competitive exclusion product Broilact against Campylobacter jejuni was evaluated in broiler chickens in a 5-week pilot-scale study. Newly-hatched broiler chicks were brought from a commercial hatchery. After arrival 50 seeder chicks were challenged orally with approximately 10(3) cfu of C. jejuni, wing marked, and placed back in a delivery box and moved to a separate room. The rest of the chicks (contact chicks) were placed in floor pens, 100 chicks per pen. Birds in two pens were treated orally on the day of hatch with the commercial competitive exclusion (CE) product Broilact, and three pens were left untreated. The following day 10 seeder chicks were introduced into the Broilact treated and untreated control pens. One pen was left both untreated and unchallenged (0-control). Each week the ceca of 10 contact chicks and one seeder chick were examined quantitatively for Campylobacter The treatment prevented or significantly reduced the colonization of the challenge organism in the ceca during the two first weeks; the percentage of colonized birds being 0% after the first week and 30% after the second week in the Broilact treated groups but was 100% in the control groups the entire 5-week rearing period. During the third rearing week the proportion of Campylobacter positive birds started to increase in the treated pens, being 80% after the third week and 95 and 90% after the fourth and fifth rearing weeks, respectively. Similarly the average count of Campylobacter in the cecal contents of the Broilact treated chicks started to increase, the difference between the treated and control chicks being 1.4 logs at the end of the rearing period. Although the protective effect was temporary and occurred only during the first two weeks of the rearing period, the results of this study support the earlier observations that CE flora designed to protect chicks from Salmonella may also reduce Campylobacter colonization of broiler chickens. © The

  10. Sorption of TCE by humic-preloaded activated carbon: Incorporating size-exclusion and pore blockage phenomenon in a competitive adsorption model

    SciTech Connect

    Kilduff, J.E.; Wigton, A.

    1999-01-15

    Naturally occurring, macromolecular dissolved organic matter (NOM) is known to foul activated carbon adsorbents, reducing the ability of fixed-bed adsorbers to efficiently remove targeted synthetic organic contaminants (SOCs). An accurate description of the effects of NOM competition on SOC adsorption equilibria is required to develop dynamic models, which have application to process design and analysis. A model was developed, using an approach based on the Ideal Adsorbed Solution Theory (IAST), to predict trichloroethylene (TCE) adsorption by activated carbon preloaded with humic acid. The IAST model was formulated for a bisolute system in which TCE and humic acid single-solute uptakes were described by the Langmuir-Freundlich and Freundlich isotherms, respectively. The humic mixture was modeled as a single component based on previous studies that identified the low-molecular-weight hydrophobic fraction as the most reactive with regard to preloading effects. Isotherms for this fraction, isolated from whole humic acid using ultrafiltration, were measured, and molar concentrations were computed based on an average molecular weight determined using size-exclusion chromatography. The IAST model was modified to reflect the hypothesis that TCE molecules can access adsorption sites which humic molecules cannot and that no competition can occur on these sites. The model was calibrated with data for TCE uptake by carbon preloaded with the low-molecular-weight humic acid fraction and was verified by predicting TCE uptake by carbon preloaded with whole humic acid. Further improvement to the model was possible by accounting for pore blockage as a mechanism which can reduce the effective surface area available in TCE.

  11. OPTIMIZING THROUGH CO-EVOLUTIONARY AVALANCHES

    SciTech Connect

    S. BOETTCHER; A. PERCUS

    2000-08-01

    We explore a new general-purpose heuristic for finding high-quality solutions to hard optimization problems. The method, called extremal optimization, is inspired by ''self-organized critically,'' a concept introduced to describe emergent complexity in many physical systems. In contrast to Genetic Algorithms which operate on an entire ''gene-pool'' of possible solutions, extremal optimization successively replaces extremely undesirable elements of a sub-optimal solution with new, random ones. Large fluctuations, called ''avalanches,'' ensue that efficiently explore many local optima. Drawing upon models used to simulate far-from-equilibrium dynamics, extremal optimization complements approximation methods inspired by equilibrium statistical physics, such as simulated annealing. With only one adjustable parameter, its performance has proved competitive with more elaborate methods, especially near phase transitions. Those phase transitions are found in the parameter space of most optimization problems, and have recently been conjectured to be the origin of some of the hardest instances in computational complexity. We will demonstrate how extremal optimization can be implemented for a variety of combinatorial optimization problems. We believe that extremal optimization will be a useful tool in the investigation of phase transitions in combinatorial optimization problems, hence valuable in elucidating the origin of computational complexity.

  12. The use of competitive exclusion in broilers to reduce the level of Salmonella contamination on the farm and at the processing plant.

    PubMed

    Palmu, L; Camelin, I

    1997-11-01

    The effect of a competitive exclusion (CE) product, Broilact, on Salmonella contamination of broiler chickens was studied on the farm and at the processing plant. In the first part of the study, two flocks per week, a CE-treated and an untreated control flock, were placed in similar broiler houses. The CE treatment was administered in the hatchery using a modified spray vaccination cabinet. Salmonella was analyzed from the paper pads of the transport boxes on arrival at the farm and from fecal samples taken 2 wk before slaughter. The results of Salmonella sampling were received for 67 flocks. The other 141 flocks of the company that were reared during the trial period were also sampled for Salmonella and the results were compared to those of treatment and control groups. Broiler performance, including mortality, weight, and feed conversion, was recorded for the trial flocks. In the second part of the study, Salmonella contamination of neck skin samples taken at the processing plant from 18 CE-treated and 28 control flocks was compared. The Broilact-treatment significantly reduced Salmonella contamination both on the farm and at the processing plant. At the level of the farm, the percentage of Salmonella-positive flocks was essentially the same in the control flocks and in other flocks reared during the trial period. An improvement in broiler performance was indicated, although the difference was not significant.

  13. Use of organic acids and competitive exclusion product as an alternative to antibiotic as a growth promoter in the raising of commercial turkeys.

    PubMed

    Milbradt, E L; Okamoto, A S; Rodrigues, J C Z; Garcia, E A; Sanfelice, C; Centenaro, L P; Andreatti Filho, R L

    2014-07-01

    A study was conducted to investigate the effects of organic acids (OA) and competitive exclusion product (CE) on growth performance, intestinal morphology, and concentration of volatile fatty acids in the cecal content. The experiment lasted for 10 wk. Four hundred twenty 1-d-old female commercial cross turkey poults (British United Turkeys, BUT Big 9) were distributed into 4 treatments with 5 replicates/pen of 21 birds each. The birds were fed a basal diet without growth promoter (control), diet with lincomycin (44 mg/kg), diet with organic acids (2 g/kg), and diet with product of CE (10(9) cfu/kg). Dietary levels of other nutrients, housing, and general management practices were similar for all treatments. On the first week (d 0-7), the BW and BW gain of the birds that fed diets with OA were lower than in the control group. In the fattening phase (d 28-70), the feed intake of the OA-treated group was lower than compared with the control. The birds that received diet with OA and CE product presented higher concentrations of propionic acid, at 14 d, and butyric acid in cecal content at 28, 56, and 70 d, compared with the control. Dietary inclusion of additives had no significant effects on intestinal villus height, crypt depth, and villus:crypt ratio. Organic acids had negative effects either on early gain or feed intake throughout the study. Because the test was conducted under controlled experimental conditions, the additives that showed results similar to those found by using antibiotics should be studied further in commercial farms to obtain results that can be incorporated into practice. © 2014 Poultry Science Association Inc.

  14. A systematic review-meta-analysis and meta-regression on the effect of selected competitive exclusion products on Salmonella spp. prevalence and concentration in broiler chickens.

    PubMed

    Kerr, Ashley K; Farrar, Ashley M; Waddell, Lisa A; Wilkins, Wendy; Wilhelm, Barbara J; Bucher, Oliver; Wills, Robert W; Bailey, R Hart; Varga, Csaba; McEwen, Scott A; Rajić, Andrijana

    2013-08-01

    The effectiveness of various competitive exclusion (CE) products for reducing Salmonella colonization in broiler chickens was evaluated using systematic review-meta-analysis-meta-regression (SR-MA-MR). Relevance screening identified 201 relevant studies that were subjected to methodological assessment. Of these studies, 159 were suitable for data extraction, 66 were presented in a number of MAs and 130 were examined in a meta-regression (MR). Fourteen different CE products were identified, 9 of them commercial products, and the most common route of administration was oral gavage (63.7% of trials). Meta-analyses indicated that a number of CE products reduce Salmonella colonization in broilers, the most effective one being Preempt™ which was formerly known as CF-3. Five study characteristics (publication year, CE type, CE route, sample origin, and Salmonella serovar administered/recovered) and three methodological soundness characteristics (treatment assignment, intervention and laboratory methods description) were retained as statistically significant (p<0.05) in the final MR model. The MR analysis indicated that, undefined CE products outperformed all commercial products, except for: Preempt™ and Broilact(®). Both were considered comparable to the undefined chicken source CE culture products in effectiveness. The administration of CE through spraying the chicks at the hatchery was determined to be just as effective as the oral gavage treatment, and more practical for farmers to administer. The results of this study could be useful in decision-making concerning the on-farm use of CE products in broiler chickens, and as inputs for risk assessments as the industry pushes for more antibiotic-free alternatives. Out of the various interventions to reduce Salmonella colonization in broilers on-farm, CE was the most studied; its inability to be licenced in certain countries and proof of consistent efficacy remains a barrier. Copyright © 2013 Elsevier B.V. All rights

  15. Cyber Security Research Frameworks For Coevolutionary Network Defense

    SciTech Connect

    Rush, George D.; Tauritz, Daniel Remy

    2015-12-03

    Several architectures have been created for developing and testing systems used in network security, but most are meant to provide a platform for running cyber security experiments as opposed to automating experiment processes. In the first paper, we propose a framework termed Distributed Cyber Security Automation Framework for Experiments (DCAFE) that enables experiment automation and control in a distributed environment. Predictive analysis of adversaries is another thorny issue in cyber security. Game theory can be used to mathematically analyze adversary models, but its scalability limitations restrict its use. Computational game theory allows us to scale classical game theory to larger, more complex systems. In the second paper, we propose a framework termed Coevolutionary Agent-based Network Defense Lightweight Event System (CANDLES) that can coevolve attacker and defender agent strategies and capabilities and evaluate potential solutions with a custom network defense simulation. The third paper is a continuation of the CANDLES project in which we rewrote key parts of the framework. Attackers and defenders have been redesigned to evolve pure strategy, and a new network security simulation is devised which specifies network architecture and adds a temporal aspect. We also add a hill climber algorithm to evaluate the search space and justify the use of a coevolutionary algorithm.

  16. Coevolutionary dynamics between tribe Cercopithecini tetherins and their lentiviruses

    PubMed Central

    Takeuchi, Junko S.; Ren, Fengrong; Yoshikawa, Rokusuke; Yamada, Eri; Nakano, Yusuke; Kobayashi, Tomoko; Matsuda, Kenta; Izumi, Taisuke; Misawa, Naoko; Shintaku, Yuta; Wetzel, Katherine S.; Collman, Ronald G.; Tanaka, Hiroshi; Hirsch, Vanessa M.; Koyanagi, Yoshio; Sato, Kei

    2015-01-01

    Human immunodeficiency virus, a primate lentivirus (PLV), causes AIDS in humans, whereas most PLVs are less or not pathogenic in monkeys. These notions suggest that the co-evolutionary process of PLVs and their hosts associates with viral pathogenicity, and therefore, that elucidating the history of virus-host co-evolution is one of the most intriguing topics in the field of virology. To address this, recent studies have focused on the interplay between intrinsic anti-viral proteins, such as tetherin, and viral antagonists. Through an experimental-phylogenetic approach, here we investigate the co-evolutionary interplay between tribe Cercopithecini tetherin and viral antagonists, Nef and Vpu. We reveal that tribe Cercopithecini tetherins are positively selected, possibly triggered by ancient Nef-like factor(s). We reconstruct the ancestral sequence of tribe Cercopithecini tetherin and demonstrate that all Nef proteins are capable of antagonizing ancestral Cercopithecini tetherin. Further, we consider the significance of evolutionary arms race between tribe Cercopithecini and their PLVs. PMID:26531727

  17. Antimicrobial residue detection in chicken yolk samples following administration to egg-producing chickens and effects of residue detection on competitive exclusion culture (PREEMPT) establishment.

    PubMed

    McReynolds, J L; Caldwell, D Y; McElroy, A P; Hargis, B M; Caldwell, D J

    2000-12-01

    Competitive exclusion (CE) cultures may offer alternatives to antimicrobial agents for disease prophylaxis in poultry. To avoid potential transfer of antibiotic resistance, safe and effective CE cultures must, by necessity, be highly sensitive to antimicrobial residues. The following studies evaluated the effect of maternal administration of selected antibiotics on the establishment of a licensed CE culture, PREEMPT. Selected antibiotics were administered to actively laying hens for a period of 7 days (experiment 1) or 9 days (experiment 2) in drinking water [sulfadimethoxine (0.05%), enrofloxacin (0.005%), and tylosin tartrate (0.05%)] or feed (sulfadimethoxine with ormetoprim, 250 ppm). In experiment 1, fertile eggs were collected daily and subjected to bioassay for detectable antimicrobial residues in yolk. Antimicrobial residues were not detected during the 7 days of treatment or the subsequent 3 days following cessation of treatment in the control, sulfadimethoxine, sulfadimethoxine with ormetoprim, or tylosin treatment groups. However, detectable residues were observed in eggs derived from enrofloxacin-treated hens on days 6 and 7 during antibiotic administration and also on days 2 and 3 post-antibiotic administration. In experiment 2, antimicrobial residues were also only detected in yolks from hens treated with enrofloxacin. Residue detection occurred on days 2-6 of antibiotic administration, on day 9 of antibiotic administration, on days 1-3 post-antibiotic administration, and also on day 7 post-antibiotic administration. A subset of eggs from each experimental group, corresponding to days 2-6 of antibiotic administration, days 4-6 post-antibiotic administration, and days 14-16 post-antibiotic administration, were pooled for incubation, and chicks hatched from these pools of fertile eggs were treated with PREEMPT at hatch. When 48-h cecal propionate concentrations were used as an index of culture establishment, reduced (P < 0.05) efficacy was observed only

  18. Effect of competitive exclusion in reducing the occurrence of Escherichia coli producing extended-spectrum β-lactamases in the ceca of broiler chicks.

    PubMed

    Nuotio, L; Schneitz, C; Nilsson, O

    2013-01-01

    Extended-spectrum β-lactamases (ESBL) and class C serine β-lactamases (pAmpC) able to hydrolyze third-generation cephalosporins are a recognized threat to the efficacy of these drugs in treating serious infections. Broiler chicks are a known source of Escherichia coli harboring genes for these enzymes. Competitive exclusion (CE) has been used for decades in Finland to prevent the colonization of broiler ceca by Salmonella, but has not been widely used in Sweden. The markedly different prevalences of ESBL- or pAmpC-producing E. coli at slaughter in broilers produced in the 2 countries suggest a potential role for CE. The present study was undertaken to determine the efficacy of a commercial CE product in reducing the colonization of broiler ceca by ESBL- or pAmpC-producing E. coli. The challenge organisms were isolated from healthy broilers in Sweden. Each E. coli strain (1 ESBL and 2 pAmpC types) was subjected to 4 replicate trials. In each trial, a group of 20 newly hatched Ross breed chicks were treated by gavage with the CE product, whereas another group of 20 was left untreated. The next day, all 40 chicks were inoculated by gavage with the E. coli strain. The chicks were reared in cardboard boxes and received feed and water ad libitum. After a week the chicks were asphyxiated with CO(2), and their ceca removed and examined for the presence of the E. coli strains. The median and quartiles of the challenge E. coli estimates in the groups were determined, and the treated and control groups were compared with the Wilcoxon 2-sample test. In each trial, a substantial and statistically significant or highly significant reduction was observed in the colonization of the ceca of CE-treated chicks by E. coli strains, compared with that of untreated control. Referring to an arbitrary criterion for high shedders presented in the literature, it was concluded that at least for the ESBL E. coli, the results were also of epidemiological relevance.

  19. Nonlinear Dynamics of Complex Coevolutionary Systems in Historical Times

    NASA Astrophysics Data System (ADS)

    Perdigão, Rui A. P.

    2016-04-01

    A new theoretical paradigm for statistical-dynamical modeling of complex coevolutionary systems is introduced, with the aim to provide historical geoscientists with a practical tool to analyse historical data and its underlying phenomenology. Historical data is assumed to represent the history of dynamical processes of physical and socio-economic nature. If processes and their governing laws are well understood, they are often treated with traditional dynamical equations: deterministic approach. If the governing laws are unknown or impracticable, the process is often treated as if being random (even if it is not): statistical approach. Although single eventful details - such as the exact spatiotemporal structure of a particular hydro-meteorological incident - may often be elusive to a detailed analysis, the overall dynamics exhibit group properties summarized by a simple set of categories or dynamical regimes at multiple scales - from local short-lived convection patterns to large-scale hydro-climatic regimes. The overwhelming microscale complexity is thus conveniently wrapped into a manageable group entity, such as a statistical distribution. In a stationary setting whereby the distribution is assumed to be invariant, alternating regimes are approachable as dynamical intermittence. For instance, in the context of bimodal climatic oscillations such as NAO and ENSO, each mode corresponds to a dynamical regime or phase. However, given external forcings or longer-term internal variability and multiscale coevolution, the structural properties of the system may change. These changes in the dynamical structure bring about a new distribution and associated regimes. The modes of yesteryear may no longer exist as such in the new structural order of the system. In this context, aside from regime intermittence, the system exhibits structural regime change. New oscillations may emerge whilst others fade into the annals of history, e.g. particular climate fluctuations during

  20. Multiagent Flight Control in Dynamic Environments with Cooperative Coevolutionary Algorithms

    NASA Technical Reports Server (NTRS)

    Colby, Mitchell; Knudson, Matthew D.; Tumer, Kagan

    2014-01-01

    Dynamic environments in which objectives and environmental features change with respect to time pose a difficult problem with regards to planning optimal paths through these environments. Path planning methods are typically computationally expensive, and are often difficult to implement in real time if system objectives are changed. This computational problem is compounded when multiple agents are present in the system, as the state and action space grows exponentially with the number of agents in the system. In this work, we use cooperative coevolutionary algorithms in order to develop policies which control agent motion in a dynamic multiagent unmanned aerial system environment such that goals and perceptions change, while ensuring safety constraints are not violated. Rather than replanning new paths when the environment changes, we develop a policy which can map the new environmental features to a trajectory for the agent while ensuring safe and reliable operation, while providing 92% of the theoretically optimal performance.

  1. Multiagent Flight Control in Dynamic Environments with Cooperative Coevolutionary Algorithms

    NASA Technical Reports Server (NTRS)

    Knudson, Matthew D.; Colby, Mitchell; Tumer, Kagan

    2014-01-01

    Dynamic flight environments in which objectives and environmental features change with respect to time pose a difficult problem with regards to planning optimal flight paths. Path planning methods are typically computationally expensive, and are often difficult to implement in real time if system objectives are changed. This computational problem is compounded when multiple agents are present in the system, as the state and action space grows exponentially. In this work, we use cooperative coevolutionary algorithms in order to develop policies which control agent motion in a dynamic multiagent unmanned aerial system environment such that goals and perceptions change, while ensuring safety constraints are not violated. Rather than replanning new paths when the environment changes, we develop a policy which can map the new environmental features to a trajectory for the agent while ensuring safe and reliable operation, while providing 92% of the theoretically optimal performance

  2. Direct coevolutionary couplings reflect biophysical residue interactions in proteins

    NASA Astrophysics Data System (ADS)

    Coucke, Alice; Uguzzoni, Guido; Oteri, Francesco; Cocco, Simona; Monasson, Remi; Weigt, Martin

    2016-11-01

    Coevolution of residues in contact imposes strong statistical constraints on the sequence variability between homologous proteins. Direct-Coupling Analysis (DCA), a global statistical inference method, successfully models this variability across homologous protein families to infer structural information about proteins. For each residue pair, DCA infers 21 × 21 matrices describing the coevolutionary coupling for each pair of amino acids (or gaps). To achieve the residue-residue contact prediction, these matrices are mapped onto simple scalar parameters; the full information they contain gets lost. Here, we perform a detailed spectral analysis of the coupling matrices resulting from 70 protein families, to show that they contain quantitative information about the physico-chemical properties of amino-acid interactions. Results for protein families are corroborated by the analysis of synthetic data from lattice-protein models, which emphasizes the critical effect of sampling quality and regularization on the biochemical features of the statistical coupling matrices.

  3. Direct coevolutionary couplings reflect biophysical residue interactions in proteins.

    PubMed

    Coucke, Alice; Uguzzoni, Guido; Oteri, Francesco; Cocco, Simona; Monasson, Remi; Weigt, Martin

    2016-11-07

    Coevolution of residues in contact imposes strong statistical constraints on the sequence variability between homologous proteins. Direct-Coupling Analysis (DCA), a global statistical inference method, successfully models this variability across homologous protein families to infer structural information about proteins. For each residue pair, DCA infers 21 × 21 matrices describing the coevolutionary coupling for each pair of amino acids (or gaps). To achieve the residue-residue contact prediction, these matrices are mapped onto simple scalar parameters; the full information they contain gets lost. Here, we perform a detailed spectral analysis of the coupling matrices resulting from 70 protein families, to show that they contain quantitative information about the physico-chemical properties of amino-acid interactions. Results for protein families are corroborated by the analysis of synthetic data from lattice-protein models, which emphasizes the critical effect of sampling quality and regularization on the biochemical features of the statistical coupling matrices.

  4. Evolution of culture-dependent discriminate sociality: a gene-culture coevolutionary model.

    PubMed

    Ihara, Yasuo

    2011-03-27

    Animals behave cooperatively towards certain conspecifics while being indifferent or even hostile to others. The distinction is made primarily according to kinship as predicted by the kin selection theory. With regards to humans, however, this is not always the case; in particular, humans sometimes exhibit a discriminate sociality on the basis of culturally transmitted traits, such as personal ornaments, languages, rituals, etc. This paper explores the possibility that the human faculty of cultural transmission and resultant cultural variation among individuals may have facilitated the evolution of discriminate sociality in humans. To this end, a gene-culture coevolutionary model is developed focusing on competition over control of resource as a context in which discriminate sociality may have evolved. Specifically, two types of culture-dependent discriminate sociality are considered: ingroup favouritism, with ingroup and outgroup being distinguished by the presence or absence of a cultural trait; and prestige hierarchies, with the prestige being conferred on the bearer of a cultural trait. The model specifies the conditions under which emergence and evolutionary stability of the two types of discriminate sociality are promoted by the presence of cultural variation among individuals.

  5. Co-evolutionary dynamics between public good producers and cheats in the bacterium Pseudomonas aeruginosa.

    PubMed

    Kümmerli, R; Santorelli, L A; Granato, E T; Dumas, Z; Dobay, A; Griffin, A S; West, S A

    2015-12-01

    The production of beneficial public goods is common in the microbial world, and so is cheating--the exploitation of public goods by nonproducing mutants. Here, we examine co-evolutionary dynamics between cooperators and cheats and ask whether cooperators can evolve strategies to reduce the burden of exploitation, and whether cheats in turn can improve their exploitation abilities. We evolved cooperators of the bacterium Pseudomonas aeruginosa, producing the shareable iron-scavenging siderophore pyoverdine, together with cheats, defective in pyoverdine production but proficient in uptake. We found that cooperators managed to co-exist with cheats in 56% of all replicates over approximately 150 generations of experimental evolution. Growth and competition assays revealed that co-existence was fostered by a combination of general adaptions to the media and specific adaptions to the co-evolving opponent. Phenotypic screening and whole-genome resequencing of evolved clones confirmed this pattern, and suggest that cooperators became less exploitable by cheats because they significantly reduced their pyoverdine investment. Cheats, meanwhile, improved exploitation efficiency through mutations blocking the costly pyoverdine-signalling pathway. Moreover, cooperators and cheats evolved reduced motility, a pattern that likely represents adaptation to laboratory conditions, but at the same time also affects social interactions by reducing strain mixing and pyoverdine sharing. Overall, we observed parallel evolution, where co-existence of cooperators and cheats was enabled by a combination of adaptations to the abiotic and social environment and their interactions.

  6. Age structure and cooperation in coevolutionary games on dynamic network

    NASA Astrophysics Data System (ADS)

    Qin, Zilong; Hu, Zhenhua; Zhou, Xiaoping; Yi, Jingzhang

    2015-04-01

    Our proposed model imitates the growth of a population and describes the age structure and the level of cooperation in games on dynamic network with continuous changes of structure and topology. The removal of nodes and links caused by age-dependent attack, together with the nodes addition standing for the newborns of population, badly ruins Matthew effect in this coevolutionary process. Though the network is generated by growth and preferential attachment, it degenerates into random network and it is no longer heterogeneous. When the removal of nodes and links is equal to the addition of nodes and links, the size of dynamic network is maintained in steady-state, so is the low level of cooperation. Severe structure variation, homogeneous topology and continuous invasion of new defection jointly make dynamic network unsuitable for the survival of cooperator even when the probability with which the newborn players initially adopt the strategy cooperation is high, while things change slightly when the connections of newborn players are restricted. Fortunately, moderate interactions in a generation trigger an optimal recovering process to encourage cooperation. The model developed in this paper outlines an explanation of the cohesion changes in the development process of an organization. Some suggestions for cooperative behavior improvement are given in the end.

  7. Understanding the coevolutionary dynamics of mutualism with population genomics.

    PubMed

    Yoder, Jeremy B

    2016-10-01

    Decades of research on the evolution of mutualism has generated a wealth of possible ways whereby mutually beneficial interactions between species persist in spite of the apparent advantages to individuals that accept the benefits of mutualism without reciprocating - but identifying how any particular empirical system is stabilized against cheating remains challenging. Different hypothesized models of mutualism stability predict different forms of coevolutionary selection, and emerging high-throughput sequencing methods allow examination of the selective histories of mutualism genes and, thereby, the form of selection acting on those genes. Here, I review the evolutionary theory of mutualism stability and identify how differing models make contrasting predictions for the population genomic diversity and geographic differentiation of mutualism-related genes. As an example of the possibilities offered by genomic data, I analyze genes with roles in the symbiosis of Medicago truncatula and nitrogen-fixing rhizobial bacteria, the first classic mutualism in which extensive genomic resources have been developed for both partners. Medicago truncatula symbiosis genes, as a group, differ from the rest of the genome, but they vary in the form of selection indicated by their diversity and differentiation - some show signs of selection expected from roles in sanctioning noncooperative symbionts, while others show evidence of balancing selection expected from coevolution with symbiont signaling factors. I then assess the current state of development for similar resources in other mutualistic interactions and look ahead to identify ways in which modern sequencing technology can best inform our understanding of mutualists and mutualism.

  8. A Multipopulation Coevolutionary Strategy for Multiobjective Immune Algorithm

    PubMed Central

    Shi, Jiao; Gong, Maoguo; Ma, Wenping; Jiao, Licheng

    2014-01-01

    How to maintain the population diversity is an important issue in designing a multiobjective evolutionary algorithm. This paper presents an enhanced nondominated neighbor-based immune algorithm in which a multipopulation coevolutionary strategy is introduced for improving the population diversity. In the proposed algorithm, subpopulations evolve independently; thus the unique characteristics of each subpopulation can be effectively maintained, and the diversity of the entire population is effectively increased. Besides, the dynamic information of multiple subpopulations is obtained with the help of the designed cooperation operator which reflects a mutually beneficial relationship among subpopulations. Subpopulations gain the opportunity to exchange information, thereby expanding the search range of the entire population. Subpopulations make use of the reference experience from each other, thereby improving the efficiency of evolutionary search. Compared with several state-of-the-art multiobjective evolutionary algorithms on well-known and frequently used multiobjective and many-objective problems, the proposed algorithm achieves comparable results in terms of convergence, diversity metrics, and running time on most test problems. PMID:24672330

  9. Building toy models of proteins using coevolutionary information

    NASA Astrophysics Data System (ADS)

    Cheng, Ryan; Raghunathan, Mohit; Onuchic, Jose

    2015-03-01

    Recent developments in global statistical methodologies have advanced the analysis of large collections of protein sequences for coevolutionary information. Coevolution between amino acids in a protein arises from compensatory mutations that are needed to maintain the stability or function of a protein over the course of evolution. This gives rise to quantifiable correlations between amino acid positions within the multiple sequence alignment of a protein family. Here, we use Direct Coupling Analysis (DCA) to infer a Potts model Hamiltonian governing the correlated mutations in a protein family to obtain the sequence-dependent interaction energies of a toy protein model. We demonstrate that this methodology predicts residue-residue interaction energies that are consistent with experimental mutational changes in protein stabilities as well as other computational methodologies. Furthermore, we demonstrate with several examples that DCA could be used to construct a structure-based model that quantitatively agrees with experimental data on folding mechanisms. This work serves as a potential framework for generating models of proteins that are enriched by evolutionary data that can potentially be used to engineer key functional motions and interactions in protein systems. This research has been supported by the NSF INSPIRE award MCB-1241332 and by the CTBP sponsored by the NSF (Grant PHY-1427654).

  10. Coevolutionary Feedbacks between Female Mating Interval and Male Allocation to Competing Sperm Traits Can Drive Evolution of Costly Polyandry.

    PubMed

    Bocedi, Greta; Reid, Jane M

    2016-03-01

    Complex coevolutionary feedbacks between female mating interval and male sperm traits have been hypothesized to explain the evolution and persistence of costly polyandry. Such feedbacks could potentially arise because polyandry creates sperm competition and consequent selection on male allocation to sperm traits, while the emerging sperm traits could create female sperm limitation and, hence, impose selection for increased polyandry. However, the hypothesis that costly polyandry could coevolve with male sperm dynamics has not been tested. We built a genetically explicit individual-based model to simulate simultaneous evolution of female mating interval and male allocation to sperm number versus longevity, where these two sperm traits trade off. We show that evolution of competing sperm traits under polyandry can indeed cause female sperm limitation and, hence, promote further evolution and persistence of costly polyandry, particularly when sperm are costly relative to the degree of female sperm limitation. These feedbacks were stronger, and greater polyandry evolved, when postcopulatory competition for paternity followed a loaded rather than fair raffle and when sperm traits had realistically low heritability. We therefore demonstrate that the evolution of allocation to sperm traits driven by sperm competition can prevent males from overcoming female sperm limitation, thereby driving ongoing evolution of costly polyandry.

  11. Coevolutionary dynamics of phenotypic diversity and contingent cooperation.

    PubMed

    Wu, Te; Wang, Long; Fu, Feng

    2017-01-01

    Phenotypic diversity is considered beneficial to the evolution of contingent cooperation, in which cooperators channel their help preferentially towards others of similar phenotypes. However, it remains largely unclear how phenotypic variation arises in the first place and thus leads to the construction of phenotypic complexity. Here we propose a mathematical model to study the coevolutionary dynamics of phenotypic diversity and contingent cooperation. Unlike previous models, our model does not assume any prescribed level of phenotypic diversity, but rather lets it be an evolvable trait. Each individual expresses one phenotype at a time and only the phenotypes expressed are visible to others. Moreover, individuals can differ in their potential of phenotypic variation, which is characterized by the number of distinct phenotypes they can randomly switch to. Each individual incurs a cost proportional to the number of potentially expressible phenotypes so as to retain phenotypic variation and expression. Our results show that phenotypic diversity coevolves with contingent cooperation under a wide range of conditions and that there exists an optimal level of phenotypic diversity best promoting contingent cooperation. It pays for contingent cooperators to elevate their potential of phenotypic variation, thereby increasing their opportunities of establishing cooperation via novel phenotypes, as these new phenotypes serve as secret tags that are difficult for defector to discover and chase after. We also find that evolved high levels of phenotypic diversity can occasionally collapse due to the invasion of defector mutants, suggesting that cooperation and phenotypic diversity can mutually reinforce each other. Thus, our results provide new insights into better understanding the coevolution of cooperation and phenotypic diversity.

  12. Coevolutionary dynamics of phenotypic diversity and contingent cooperation

    PubMed Central

    Wang, Long

    2017-01-01

    Phenotypic diversity is considered beneficial to the evolution of contingent cooperation, in which cooperators channel their help preferentially towards others of similar phenotypes. However, it remains largely unclear how phenotypic variation arises in the first place and thus leads to the construction of phenotypic complexity. Here we propose a mathematical model to study the coevolutionary dynamics of phenotypic diversity and contingent cooperation. Unlike previous models, our model does not assume any prescribed level of phenotypic diversity, but rather lets it be an evolvable trait. Each individual expresses one phenotype at a time and only the phenotypes expressed are visible to others. Moreover, individuals can differ in their potential of phenotypic variation, which is characterized by the number of distinct phenotypes they can randomly switch to. Each individual incurs a cost proportional to the number of potentially expressible phenotypes so as to retain phenotypic variation and expression. Our results show that phenotypic diversity coevolves with contingent cooperation under a wide range of conditions and that there exists an optimal level of phenotypic diversity best promoting contingent cooperation. It pays for contingent cooperators to elevate their potential of phenotypic variation, thereby increasing their opportunities of establishing cooperation via novel phenotypes, as these new phenotypes serve as secret tags that are difficult for defector to discover and chase after. We also find that evolved high levels of phenotypic diversity can occasionally collapse due to the invasion of defector mutants, suggesting that cooperation and phenotypic diversity can mutually reinforce each other. Thus, our results provide new insights into better understanding the coevolution of cooperation and phenotypic diversity. PMID:28141806

  13. Predation and eukaryote cell origins: a coevolutionary perspective.

    PubMed

    Cavalier-Smith, T

    2009-02-01

    Cells are of only two kinds: bacteria, with DNA segregated by surface membrane motors, dating back approximately 3.5Gy; and eukaryotes, which evolved from bacteria, possibly as recently as 800-850My ago. The last common ancestor of eukaryotes was a sexual phagotrophic protozoan with mitochondria, one or two centrioles and cilia. Conversion of bacteria (=prokaryotes) into a eukaryote involved approximately 60 major innovations. Numerous contradictory ideas about eukaryogenesis fail to explain fundamental features of eukaryotic cell biology or conflict with phylogeny. Data are best explained by the intracellular coevolutionary theory, with three basic tenets: (1) the eukaryotic cytoskeleton and endomembrane system originated through cooperatively enabling the evolution of phagotrophy; (2) phagocytosis internalised DNA-membrane attachments, unavoidably disrupting bacterial division; recovery entailed the evolution of the nucleus and mitotic cycle; (3) the symbiogenetic origin of mitochondria immediately followed the perfection of phagotrophy and intracellular digestion, contributing greater energy efficiency and group II introns as precursors of spliceosomal introns. Eukaryotes plus their archaebacterial sisters form the clade neomura, which evolved from a radically modified derivative of an actinobacterial posibacterium that had replaced the ancestral eubacterial murein peptidoglycan by N-linked glycoproteins, radically modified its DNA-handling enzymes, and evolved cotranslational protein secretion, but not the isoprenoid-ether lipids of archaebacteria. I focus on this phylogenetic background and on explaining how in response to novel phagotrophic selective pressures and ensuing genome internalisation this prekaryote evolved efficient digestion of prey proteins by retrotranslocation and 26S proteasomes, then internal digestion by phagocytosis, lysosomes, and peroxisomes, and eukaryotic vesicle trafficking and intracellular compartmentation.

  14. Are the metabolomic responses to folivory of closely related plant species linked to macroevolutionary and plant-folivore coevolutionary processes?

    SciTech Connect

    Rivas-Ubach, Albert; Hódar, José A.; Sardans, Jordi; Kyle, Jennifer E.; Kim, Young-Mo; Oravec, Michal; Urban, Otmar; Guenther, Alex; Peñuelas, Josep

    2016-06-02

    The debate whether the coevolution of plants and insects or macroevolutionary processes (phylogeny) is the main driver determining the arsenal of molecular defensive compounds of plants remains unresolved. Attacks by herbivorous insects affect not only the composition of defensive compounds in plants but the entire metabolome (the set of molecular metabolites), including defensive compounds. Metabolomes are the final products of genotypes and are directly affected by macroevolutionary processes, so closely related species should have similar metabolomic compositions and may respond in similar ways to attacks by folivores. We analyzed the elemental compositions and metabolomes of needles from Pinus pinaster, P. nigra and P. sylvestris to determine if these closely related Pinus species with different coevolutionary histories with the caterpillars of the processionary moth respond similarly to attacks by this lepidopteran. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the pine species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of phenolic metabolites were generally not higher in the attacked trees, which had lower concentrations of terpenes, suggesting that herbivores avoid individuals with high concentrations of terpenes. Our results suggest that macroevolutionary history plays important roles in the metabolomic responses of these pine species to folivory, but plant-insect coevolution probably constrains those responses. Combinations of different evolutionary factors and trade-offs are likely responsible for the different responses of each species to folivory, which is not necessarily exclusively linked to plant-insect coevolution.

  15. Coevolutionary dynamics of polyandry and sex-linked meiotic drive.

    PubMed

    Holman, Luke; Price, Thomas A R; Wedell, Nina; Kokko, Hanna

    2015-03-01

    Segregation distorters located on sex chromosomes are predicted to sweep to fixation and cause extinction via a shortage of one sex, but in nature they are often found at low, stable frequencies. One potential resolution to this longstanding puzzle involves female multiple mating (polyandry). Because many meiotic drivers severely reduce the sperm competitive ability of their male carriers, females are predicted to evolve more frequent polyandry and thereby promote sperm competition when a meiotic driver invades. Consequently, the driving chromosome's relative fitness should decline, halting or reversing its spread. We used formal modeling to show that this initially appealing hypothesis cannot resolve the puzzle alone: other selective pressures (e.g., low fitness of drive homozygotes) are required to establish a stable meiotic drive polymorphism. However, polyandry and meiotic drive can strongly affect one another's frequency, and polyandrous populations may be resistant to the invasion of rare drive mutants. © 2015 The Author(s).

  16. Fine-tuned Bee-Flower Coevolutionary State Hidden within Multiple Pollination Interactions

    PubMed Central

    Shimizu, Akira; Dohzono, Ikumi; Nakaji, Masayoshi; Roff, Derek A.; Miller III, Donald G.; Osato, Sara; Yajima, Takuya; Niitsu, Shûhei; Utsugi, Nozomu; Sugawara, Takashi; Yoshimura, Jin

    2014-01-01

    Relationships between flowers and pollinators are generally considered cases of mutualism since both agents gain benefits. Fine-tuned adaptations are usually found in the form of strict one-to-one coevolution between species. Many insect pollinators are, however, considered generalists, visiting numerous kinds of flowers, and many flower species (angiosperms) are also considered generalists, visited by many insect pollinators. We here describe a fine-tuned coevolutionary state of a flower-visiting bee that collects both nectar and pollen from an early spring flower visited by multiple pollinators. Detailed morphology of the bee proboscis is shown to be finely adjusted to the floral morphology and nectar production of the flower. Behavioral observations also confirm the precision of this mutualism. Our results suggest that a fine-tuned one-to-one coevolutionary state between a flower species and a pollinator species might be common, but frequently overlooked, in multiple flower-pollinator interactions. PMID:24496444

  17. Optimal satellite formation reconfiguration using co-evolutionary particle swarm optimization in deep space

    NASA Astrophysics Data System (ADS)

    Huang, Haibin; Zhuang, Yufei

    2015-08-01

    This paper proposes a method that plans energy-optimal trajectories for multi-satellite formation reconfiguration in deep space environment. A novel co-evolutionary particle swarm optimization algorithm is stated to solve the nonlinear programming problem, so that the computational complexity of calculating the gradient information could be avoided. One swarm represents one satellite, and through communication with other swarms during the evolution, collisions between satellites can be avoided. In addition, a dynamic depth first search algorithm is proposed to solve the redundant search problem of a co-evolutionary particle swarm optimization method, with which the computation time can be shorten a lot. In order to make the actual trajectories optimal and collision-free with disturbance, a re-planning strategy is deduced for formation reconfiguration maneuver.

  18. Co-evolutionary Data Mining in Phase Space for Robust Fuzzy Resource Management

    DTIC Science & Technology

    2004-07-01

    function under their own autonomous logic or human control. This approach automates the data mining problem. The game automatically creates a cleansed...database reflecting the domain expert’s knowledge, it calls a data mining function, a genetic algorithm for data mining of the data base as required and...discussed. The strategy tree concept and its relationship to co-evolutionary data mining are examined as well as the associated phase space

  19. Network intrusion detection by the coevolutionary immune algorithm of artificial immune systems with clonal selection

    NASA Astrophysics Data System (ADS)

    Salamatova, T.; Zhukov, V.

    2017-02-01

    The paper presents the application of the artificial immune systems apparatus as a heuristic method of network intrusion detection for algorithmic provision of intrusion detection systems. The coevolutionary immune algorithm of artificial immune systems with clonal selection was elaborated. In testing different datasets the empirical results of evaluation of the algorithm effectiveness were achieved. To identify the degree of efficiency the algorithm was compared with analogs. The fundamental rules based of solutions generated by this algorithm are described in the article.

  20. 48 CFR 19.1006 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Exclusions. 19.1006 Section 19.1006 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Small Business Competitiveness Demonstration Program 19.1006 Exclusions...

  1. Coevolutionary Analysis Identifies Protein–Protein Interaction Sites between HIV-1 Reverse Transcriptase and Integrase

    PubMed Central

    Hetti Arachchilage, Madara; Piontkivska, Helen

    2016-01-01

    The replication of human immunodeficiency virus-1 (HIV-1) requires reverse transcription of the viral RNA genome and integration of newly synthesized pro-viral DNA into the host genome. This is mediated by the viral proteins reverse transcriptase (RT) and integrase (IN). The formation and stabilization of the pre-integration complex (PIC), which is an essential step for reverse transcription, nuclear import, chromatin targeting, and subsequent integration, involves direct and indirect modes of interaction between RT and IN proteins. While epitope-based treatments targeting IN–viral DNA and IN–RT complexes appear to be a promising combination for an anti-HIV treatment, the mechanisms of IN-RT interactions within the PIC are not well understood due to the transient nature of the protein complex and the intrinsic flexibility of its components. Here, we identify potentially interacting regions between the IN and RT proteins within the PIC through the coevolutionary analysis of amino acid sequences of the two proteins. Our results show that specific regions in the two proteins have strong coevolutionary signatures, suggesting that these regions either experience direct and prolonged interactions between them that require high affinity and/or specificity or that the regions are involved in interactions mediated by dynamic conformational changes and, hence, may involve both direct and indirect interactions. Other regions were found to exhibit weak, but positive correlations, implying interactions that are likely transient and/or have low affinity. We identified a series of specific regions of potential interactions between the IN and RT proteins (e.g., specific peptide regions within the C-terminal domain of IN were identified as potentially interacting with the Connection domain of RT). Coevolutionary analysis can serve as an important step in predicting potential interactions, thus informing experimental studies. These studies can be integrated with structural data

  2. Dynamic control and information processing in the Belousov-Zhabotinsky reaction using a coevolutionary algorithm.

    PubMed

    Toth, Rita; Stone, Christopher; Adamatzky, Andrew; de Lacy Costello, Ben; Bull, Larry

    2008-11-14

    We propose that the behavior of nonlinear media can be controlled dynamically through coevolutionary systems. In this study, a light-sensitive subexcitable Belousov-Zhabotinsky reaction is controlled using a heterogeneous cellular automaton. A checkerboard image comprising of varying light intensity cells is projected onto the surface of a catalyst-loaded gel resulting in rich spatiotemporal chemical wave behavior. The coevolved cellular automaton is shown to be able to either increase or decrease chemical activity through dynamic control of the light intensity within each cell in both simulated and real chemical systems. The approach is then extended to construct a number of simple logical functions.

  3. Natural Hazard Management from a Coevolutionary Perspective: Exposure and Policy Response in the European Alps

    PubMed Central

    Fuchs, Sven; Röthlisberger, Veronika; Thaler, Thomas; Zischg, Andreas; Keiler, Margreth

    2017-01-01

    A coevolutionary perspective is adopted to understand the dynamics of exposure to mountain hazards in the European Alps. A spatially explicit, object-based temporal assessment of elements at risk to mountain hazards (river floods, torrential floods, and debris flows) in Austria and Switzerland is presented for the period from 1919 to 2012. The assessment is based on two different data sets: (1) hazard information adhering to legally binding land use planning restrictions and (2) information on building types combined from different national-level spatial data. We discuss these transdisciplinary dynamics and focus on economic, social, and institutional interdependencies and interactions between human and physical systems. Exposure changes in response to multiple drivers, including population growth and land use conflicts. The results show that whereas some regional assets are associated with a strong increase in exposure to hazards, others are characterized by a below-average level of exposure. The spatiotemporal results indicate relatively stable hot spots in the European Alps. These results coincide with the topography of the countries and with the respective range of economic activities and political settings. Furthermore, the differences between management approaches as a result of multiple institutional settings are discussed. A coevolutionary framework widens the explanatory power of multiple drivers to changes in exposure and risk and supports a shift from structural, security-based policies toward an integrated, risk-based natural hazard management system. PMID:28267154

  4. Coevolutionary arms race versus host defense chase in a tropical herbivore-plant system.

    PubMed

    Endara, María-José; Coley, Phyllis D; Ghabash, Gabrielle; Nicholls, James A; Dexter, Kyle G; Donoso, David A; Stone, Graham N; Pennington, R Toby; Kursar, Thomas A

    2017-09-05

    Coevolutionary models suggest that herbivores drive diversification and community composition in plants. For herbivores, many questions remain regarding how plant defenses shape host choice and community structure. We addressed these questions using the tree genus Inga and its lepidopteran herbivores in the Amazon. We constructed phylogenies for both plants and insects and quantified host associations and plant defenses. We found that similarity in herbivore assemblages between Inga species was correlated with similarity in defenses. There was no correlation with phylogeny, a result consistent with our observations that the expression of defenses in Inga is independent of phylogeny. Furthermore, host defensive traits explained 40% of herbivore community similarity. Analyses at finer taxonomic scales showed that different lepidopteran clades select hosts based on different defenses, suggesting taxon-specific histories of herbivore-host plant interactions. Finally, we compared the phylogeny and defenses of Inga to phylogenies for the major lepidopteran clades. We found that closely related herbivores fed on Inga with similar defenses rather than on closely related plants. Together, these results suggest that plant defenses might be more evolutionarily labile than the herbivore traits related to host association. Hence, there is an apparent asymmetry in the evolutionary interactions between Inga and its herbivores. Although plants may evolve under selection by herbivores, we hypothesize that herbivores may not show coevolutionary adaptations, but instead "chase" hosts based on the herbivore's own traits at the time that they encounter a new host, a pattern more consistent with resource tracking than with the arms race model of coevolution.

  5. An Improved Co-evolutionary Particle Swarm Optimization for Wireless Sensor Networks with Dynamic Deployment

    PubMed Central

    Wang, Xue; Wang, Sheng; Ma, Jun-Jie

    2007-01-01

    The effectiveness of wireless sensor networks (WSNs) depends on the coverage and target detection probability provided by dynamic deployment, which is usually supported by the virtual force (VF) algorithm. However, in the VF algorithm, the virtual force exerted by stationary sensor nodes will hinder the movement of mobile sensor nodes. Particle swarm optimization (PSO) is introduced as another dynamic deployment algorithm, but in this case the computation time required is the big bottleneck. This paper proposes a dynamic deployment algorithm which is named “virtual force directed co-evolutionary particle swarm optimization” (VFCPSO), since this algorithm combines the co-evolutionary particle swarm optimization (CPSO) with the VF algorithm, whereby the CPSO uses multiple swarms to optimize different components of the solution vectors for dynamic deployment cooperatively and the velocity of each particle is updated according to not only the historical local and global optimal solutions, but also the virtual forces of sensor nodes. Simulation results demonstrate that the proposed VFCPSO is competent for dynamic deployment in WSNs and has better performance with respect to computation time and effectiveness than the VF, PSO and VFPSO algorithms.

  6. Coevolutionary diversification creates nested-modular structure in phage-bacteria interaction networks.

    PubMed

    Beckett, Stephen J; Williams, Hywel T P

    2013-12-06

    Phage and their bacterial hosts are the most diverse and abundant biological entities in the oceans, where their interactions have a major impact on marine ecology and ecosystem function. The structure of interaction networks for natural phage-bacteria communities offers insight into their coevolutionary origin. At small phylogenetic scales, observed communities typically show a nested structure, in which both hosts and phages can be ranked by their range of resistance and infectivity, respectively. A qualitatively different multi-scale structure is seen at larger phylogenetic scales; a natural assemblage sampled from the Atlantic Ocean displays large-scale modularity and local nestedness within each module. Here, we show that such 'nested-modular' interaction networks can be produced by a simple model of host-phage coevolution in which infection depends on genetic matching. Negative frequency-dependent selection causes diversification of hosts (to escape phages) and phages (to track their evolving hosts). This creates a diverse community of bacteria and phage, maintained by kill-the-winner ecological dynamics. When the resulting communities are visualized as bipartite networks of who infects whom, they show the nested-modular structure characteristic of the Atlantic sample. The statistical significance and strength of this observation varies depending on whether the interaction networks take into account the density of the interacting strains, with implications for interpretation of interaction networks constructed by different methods. Our results suggest that the apparently complex community structures associated with marine bacteria and phage may arise from relatively simple coevolutionary origins.

  7. Natural Hazard Management from a Coevolutionary Perspective: Exposure and Policy Response in the European Alps.

    PubMed

    Fuchs, Sven; Röthlisberger, Veronika; Thaler, Thomas; Zischg, Andreas; Keiler, Margreth

    2017-03-04

    A coevolutionary perspective is adopted to understand the dynamics of exposure to mountain hazards in the European Alps. A spatially explicit, object-based temporal assessment of elements at risk to mountain hazards (river floods, torrential floods, and debris flows) in Austria and Switzerland is presented for the period from 1919 to 2012. The assessment is based on two different data sets: (1) hazard information adhering to legally binding land use planning restrictions and (2) information on building types combined from different national-level spatial data. We discuss these transdisciplinary dynamics and focus on economic, social, and institutional interdependencies and interactions between human and physical systems. Exposure changes in response to multiple drivers, including population growth and land use conflicts. The results show that whereas some regional assets are associated with a strong increase in exposure to hazards, others are characterized by a below-average level of exposure. The spatiotemporal results indicate relatively stable hot spots in the European Alps. These results coincide with the topography of the countries and with the respective range of economic activities and political settings. Furthermore, the differences between management approaches as a result of multiple institutional settings are discussed. A coevolutionary framework widens the explanatory power of multiple drivers to changes in exposure and risk and supports a shift from structural, security-based policies toward an integrated, risk-based natural hazard management system.

  8. The evolution of mutation rate in an antagonistic coevolutionary model with maternal transmission of parasites.

    PubMed

    Greenspoon, Philip B; M'Gonigle, Leithen K

    2013-06-22

    By constantly selecting for novel genotypes, coevolution between hosts and parasites can favour elevated mutation rates. Models of this process typically assume random encounters. However, offspring are often more likely to encounter their mother's parasites. Because parents and offspring are genetically similar, they may be susceptible to the same parasite strains and thus, in hosts, maternal transmission should select for mechanisms that decrease intergenerational genetic similarity. In parasites, however, maternal transmission should select for genetic similarity. We develop and analyse a model of host and parasite mutation rate evolution when parasites are maternally inherited. In hosts, we find that maternal transmission has two opposing effects. First, it eliminates coevolutionary cycles that previous work shows select for higher mutation. Second, it independently selects for higher mutation rates, because offspring that differ from their mothers are more likely to avoid infection. In parasites, however, the two effects of maternal transmission act in the same direction. As for hosts, maternal transmission eliminates coevolutionary cycles, thereby reducing selection for increased mutation. Unlike for hosts, however, maternal transmission additionally selects against higher mutation by favouring parasite offspring that are the same as their mothers.

  9. Flood hazard management from a coevolutionary perspective: exposure and policy response in the European Alps

    NASA Astrophysics Data System (ADS)

    Fuchs, Sven; Röthlisberger, Veronika; Thaler, Thomas; Zischg, Andreas; Keiler, Margreth

    2017-04-01

    A coevolutionary perspective is adopted to understand the dynamics of exposure to hydrological hazards in the European Alps. A spatially explicit, object-based temporal assessment of elements at risk to flood hazards (river floods, torrential floods and debris flows) in Austria and Switzerland is presented for the 1919-2012 period. The assessment is based on two different datasets, (a) hazard information adhering to legally binding land use planning restrictions and (b) information on building types combined from different national level spatial data. We discuss these transdisciplinary dynamics and focus on economic, social and institutional interdependencies and interactions between human and physical systems. Exposure changes in the response to multiple drivers, including population growth and land use conflicts. The results show that while some regional assets are associated with a strong increase in exposure to hazards, others are characterized by a below-average level of exposure. The spatiotemporal results indicate relatively stable hot spots in the European Alps. These results coincide with the topography of the countries and with the respective range of economic activities and political settings. Furthermore, the differences between management approaches as a result of multiple institutional settings are discussed. A coevolutionary framework widens the explanatory power of multiple drivers to changes in exposure and risk, and supports a shift from structural, security-based policies towards an integrated, risk-based natural hazard management system.

  10. A probabilistic coevolutionary biclustering algorithm for discovering coherent patterns in gene expression dataset

    PubMed Central

    2012-01-01

    Background Biclustering has been utilized to find functionally important patterns in biological problem. Here a bicluster is a submatrix that consists of a subset of rows and a subset of columns in a matrix, and contains homogeneous patterns. The problem of finding biclusters is still challengeable due to computational complex trying to capture patterns from two-dimensional features. Results We propose a Probabilistic COevolutionary Biclustering Algorithm (PCOBA) that can cluster the rows and columns in a matrix simultaneously by utilizing a dynamic adaptation of multiple species and adopting probabilistic learning. In biclustering problems, a coevolutionary search is suitable since it can optimize interdependent subcomponents formed of rows and columns. Furthermore, acquiring statistical information on two populations using probabilistic learning can improve the ability of search towards the optimum value. We evaluated the performance of PCOBA on synthetic dataset and yeast expression profiles. The results demonstrated that PCOBA outperformed previous evolutionary computation methods as well as other biclustering methods. Conclusions Our approach for searching particular biological patterns could be valuable for systematically understanding functional relationships between genes and other biological components at a genome-wide level. PMID:23282075

  11. The bitterling-mussel coevolutionary relationship in areas of recent and ancient sympatry.

    PubMed

    Reichard, Martin; Polačik, Matej; Tarkan, Ali Serhan; Spence, Rowena; Gaygusuz, Ozcan; Ercan, Ertan; Ondračková, Markéta; Smith, Carl

    2010-10-01

    Host-parasite relationships are often characterized by the rapid evolution of parasite adaptations to exploit their host, and counteradaptations in the host to avoid the costs imposed by parasitism. Hence, the current coevolutionary state between a parasite and its hosts is predicted to vary according to the history of sympatry and local abundance of interacting species. We compared a unique reciprocal coevolutionary relationship of a fish, the European bitterling (Rhodeus amarus) and freshwater mussels (Unionidae) between areas of recent (Central Europe) and ancient (Turkey) sympatry. Bitterling parasitize freshwater mussels by laying their eggs in the gills of mussel and, in turn, mussel larvae (glochidia) parasitize the fish. We found that all bitterling from both regions avoided one mussel species. Preferences among other mussel species tended to be related to local mussel abundance rather than duration of sympatry. Individual fish were not consistent in their oviposition choices, precluding the evolution of host-specific lineages. Mussels were demonstrated to have evolved strong defenses to bitterling parasitism in the area of ancient sympatry, but have no such defenses in the large areas of Europe where bitterling are currently invasive. Bitterling avoided glochidia infection irrespective of the duration of sympatry.

  12. Vulnerability from a co-evolutionary perspective: valuating natural hazards management in the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Thaler, Thomas; Fuchs, Sven

    2014-05-01

    In past decades, we observed a change in natural hazard management from a structural, security-based policy towards an integrated, risk-based management system. Therefore, the concept of vulnerability has become central in the policy debate. In order to assess vulnerability, we need a broader understanding of the term to manage natural hazards and to reduce damages and losses from future events. This paper adopts a co-evolutionary perspective to provide a critical assessment of vulnerability in natural hazard management, taking the Eastern Alps as an example. We discuss the structural, social and institutional vulnerability and governance from an integrated point of view to understand and to analyse the interdependences and interactions between human and physical systems. The aim is to consider the dynamic interactions between multiple conceptualised vulnerabilities in evaluating natural hazard management systems. A co-evolutionary framework widens the explanatory of multiple interactions in vulnerability to provide useful information and concepts to improve risk management. Keywords: vulnerability; co-evolution; natural hazards; Eastern Alps

  13. Migratory behavior of birds affects their coevolutionary relationship with blood parasites.

    PubMed

    Jenkins, Tania; Thomas, Gavin H; Hellgren, Olof; Owens, Ian P F

    2012-03-01

    Host traits, such as migratory behavior, could facilitate the dispersal of disease-causing parasites, potentially leading to the transfer of infections both across geographic areas and between host species. There is, however, little quantitative information on whether variation in such host attributes does indeed affect the evolutionary outcome of host-parasite associations. Here, we employ Leucocytozoon blood parasites of birds, a group of parasites closely related to avian malaria, to study host-parasite coevolution in relation to host behavior using a phylogenetic comparative approach. We reconstruct the molecular phylogenies of both the hosts and parasites and use cophylogenetic tools to assess whether each host-parasite association contributes significantly to the overall congruence between the two phylogenies. We find evidence for a significant fit between host and parasite phylogenies in this system, but show that this is due only to associations between nonmigrant parasites and their hosts. We also show that migrant bird species harbor a greater genetic diversity of parasites compared with nonmigrant species. Taken together, these results suggest that the migratory habits of birds could influence their coevolutionary relationship with their parasites, and that consideration of host traits is important in predicting the outcome of coevolutionary interactions.

  14. 47 CFR 22.201 - Paging geographic area authorizations are subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Licensing Requirements and Procedures Competitive.... Mutually exclusive initial applications for paging geographic area licenses are subject to competitive...

  15. The Conundrum of Modern Art : Prestige-Driven Coevolutionary Aesthetics Trumps Evolutionary Aesthetics among Art Experts.

    PubMed

    Verpooten, Jan; Dewitte, Siegfried

    2017-03-01

    Two major mechanisms of aesthetic evolution have been suggested. One focuses on naturally selected preferences (Evolutionary Aesthetics), while the other describes a process of evaluative coevolution whereby preferences coevolve with signals. Signaling theory suggests that expertise moderates these mechanisms. In this article we set out to verify this hypothesis in the domain of art and use it to elucidate Western modern art's deviation from naturally selected preferences. We argue that this deviation is consistent with a Coevolutionary Aesthetics mechanism driven by prestige-biased social learning among art experts. In order to test this hypothesis, we conducted two studies in which we assessed the effects on lay and expert appreciation of both the biological relevance of the given artwork's depicted content, viz., facial beauty, and the prestige specific to the artwork's associated context (MoMA). We found that laypeople appreciate artworks based on their depictions of facial beauty, mediated by aesthetic pleasure, which is consistent with previous studies. In contrast, experts appreciate the artworks based on the prestige of the associated context, mediated by admiration for the artist. Moreover, experts appreciate artworks depicting neutral faces to a greater degree than artworks depicting attractive faces. These findings thus corroborate our contention that expertise moderates the Evolutionary and Coevolutionary Aesthetics mechanisms in the art domain. Furthermore, our findings provide initial support for our proposal that prestige-driven coevolution with expert evaluations plays a decisive role in modern art's deviation from naturally selected preferences. After discussing the limitations of our research as well as the relation that our results bear on cultural evolution theory, we provide a number of suggestions for further research into the potential functions of expert appreciation that deviates from naturally selected preferences, on the one hand, and

  16. Competition-Colonization Trade-Offs, Competitive Uncertainty, and the Evolutionary Assembly of Species

    PubMed Central

    Pillai, Pradeep; Guichard, Frédéric

    2012-01-01

    We utilize a standard competition-colonization metapopulation model in order to study the evolutionary assembly of species. Based on earlier work showing how models assuming strict competitive hierarchies will likely lead to runaway evolution and self-extinction for all species, we adopt a continuous competition function that allows for levels of uncertainty in the outcome of competition. We then, by extending the standard patch-dynamic metapopulation model in order to include evolutionary dynamics, allow for the coevolution of species into stable communities composed of species with distinct limiting similarities. Runaway evolution towards stochastic extinction then becomes a limiting case controlled by the level of competitive uncertainty. We demonstrate how intermediate competitive uncertainty maximizes the equilibrium species richness as well as maximizes the adaptive radiation and self-assembly of species under adaptive dynamics with mutations of non-negligible size. By reconciling competition-colonization tradeoff theory with co-evolutionary dynamics, our results reveal the importance of intermediate levels of competitive uncertainty for the evolutionary assembly of species. PMID:22448253

  17. Social exclusion: the interplay of group goals and individual characteristics.

    PubMed

    Richardson, Cameron B; Hitti, Aline; Mulvey, Kelly Lynn; Killen, Melanie

    2014-08-01

    Past research has shown that adolescents justify social exclusion based on concerns for group functioning, and yet, to date, no study has evaluated whether group functioning justifications shift or remain stable across different exclusion contexts. In this study, we systematically manipulated exclusion context (i.e., competitive or noncompetitive soccer groups) and individual characteristics of the target of exclusion to test the nature of the interaction between these factors during exclusion judgments. Adolescents' (N = 201; 61% Female) exclusion judgments differed across contexts only when an individual's ability was under consideration. Intergroup (i.e., gender, nationality) and interpersonal (i.e., aggression, shyness) characteristics overwhelmed contextual considerations. Results indicate the complexity of factors weighed by adolescents when making exclusion judgments, and suggest the need for extension of the present findings to understand more fully the interaction between the context of exclusion and individual characteristics in exclusion judgments.

  18. 37 CFR 404.7 - Exclusive, co-exclusive and partially exclusive licenses.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Exclusive, co-exclusive and... Exclusive, co-exclusive and partially exclusive licenses. (a)(1) Exclusive, co-exclusive or partially... practical application or otherwise promote the invention's utilization by the public. (B) Exclusive,...

  19. 37 CFR 404.7 - Exclusive, co-exclusive and partially exclusive licenses.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Exclusive, co-exclusive and..., co-exclusive and partially exclusive licenses. (a)(1) Exclusive, co-exclusive or partially exclusive... practical application or otherwise promote the invention's utilization by the public. (B) Exclusive,...

  20. 37 CFR 404.7 - Exclusive, co-exclusive and partially exclusive licenses.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Exclusive, co-exclusive and... Exclusive, co-exclusive and partially exclusive licenses. (a)(1) Exclusive, co-exclusive or partially... practical application or otherwise promote the invention's utilization by the public. (B) Exclusive,...

  1. 37 CFR 404.7 - Exclusive, co-exclusive and partially exclusive licenses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Exclusive, co-exclusive and... Exclusive, co-exclusive and partially exclusive licenses. (a)(1) Exclusive, co-exclusive or partially... practical application or otherwise promote the invention's utilization by the public. (B) Exclusive,...

  2. 37 CFR 404.7 - Exclusive, co-exclusive and partially exclusive licenses.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Exclusive, co-exclusive and..., co-exclusive and partially exclusive licenses. (a)(1) Exclusive, co-exclusive or partially exclusive... practical application or otherwise promote the invention's utilization by the public. (B) Exclusive,...

  3. The evolution of sex and recombination in response to abiotic or coevolutionary fluctuations in epistasis.

    PubMed

    Gandon, Sylvain; Otto, Sarah P

    2007-04-01

    Evolutionary biologists have identified several factors that could explain the widespread phenomena of sex and recombination. One hypothesis is that host-parasite interactions favor sex and recombination because they favor the production of rare genotypes. A problem with many of the early models of this so-called Red Queen hypothesis is that several factors are acting together: directional selection, fluctuating epistasis, and drift. It is thus difficult to identify what exactly is selecting for sex in these models. Is one factor more important than the others or is it the synergistic action of these different factors that really matters? Here we focus on the analysis of a simple model with a single mechanism that might select for sex: fluctuating epistasis. We first analyze the evolution of sex and recombination when the temporal fluctuations are driven by the abiotic environment. We then analyze the evolution of sex and recombination in a two-species coevolutionary model, where directional selection is absent (allele frequencies remain fixed) and temporal variation in epistasis is induced by coevolution with the antagonist species. In both cases we contrast situations with weak and strong selection and derive the evolutionarily stable (ES) recombination rate. The ES recombination rate is most sensitive to the period of the cycles, which in turn depends on the strength of epistasis. In particular, more virulent parasites cause more rapid cycles and consequently increase the ES recombination rate of the host. Although the ES strategy is maximized at an intermediate period, some recombination is favored even when fluctuations are very slow. By contrast, the amplitude of the cycles has no effect on the ES level of sex and recombination, unless sex and recombination are costly, in which case higher-amplitude cycles allow the evolution of higher rates of sex and recombination. In the coevolutionary model, the amount of recombination in the interacting species also has

  4. Molecular evolution of rbcL in three gymnosperm families: identifying adaptive and coevolutionary patterns

    PubMed Central

    2011-01-01

    Background The chloroplast-localized ribulose-1, 5-biphosphate carboxylase/oxygenase (Rubisco), the primary enzyme responsible for autotrophy, is instrumental in the continual adaptation of plants to variations in the concentrations of CO2. The large subunit (LSU) of Rubisco is encoded by the chloroplast rbcL gene. Although adaptive processes have been previously identified at this gene, characterizing the relationships between the mutational dynamics at the protein level may yield clues on the biological meaning of such adaptive processes. The role of such coevolutionary dynamics in the continual fine-tuning of RbcL remains obscure. Results We used the timescale and phylogenetic analyses to investigate and search for processes of adaptive evolution in rbcL gene in three gymnosperm families, namely Podocarpaceae, Taxaceae and Cephalotaxaceae. To understand the relationships between regions identified as having evolved under adaptive evolution, we performed coevolutionary analyses using the software CAPS. Importantly, adaptive processes were identified at amino acid sites located on the contact regions among the Rubisco subunits and on the interface between Rubisco and its activase. Adaptive amino acid replacements at these regions may have optimized the holoenzyme activity. This hypothesis was pinpointed by evidence originated from our analysis of coevolution that supported the correlated evolution between Rubisco and its activase. Interestingly, the correlated adaptive processes between both these proteins have paralleled the geological variation history of the concentration of atmospheric CO2. Conclusions The gene rbcL has experienced bursts of adaptations in response to the changing concentration of CO2 in the atmosphere. These adaptations have emerged as a result of a continuous dynamic of mutations, many of which may have involved innovation of functional Rubisco features. Analysis of the protein structure and the functional implications of such mutations put

  5. Molecular evolution of rbcL in three gymnosperm families: identifying adaptive and coevolutionary patterns.

    PubMed

    Sen, Lin; Fares, Mario A; Liang, Bo; Gao, Lei; Wang, Bo; Wang, Ting; Su, Ying-Juan

    2011-06-03

    The chloroplast-localized ribulose-1, 5-biphosphate carboxylase/oxygenase (Rubisco), the primary enzyme responsible for autotrophy, is instrumental in the continual adaptation of plants to variations in the concentrations of CO2. The large subunit (LSU) of Rubisco is encoded by the chloroplast rbcL gene. Although adaptive processes have been previously identified at this gene, characterizing the relationships between the mutational dynamics at the protein level may yield clues on the biological meaning of such adaptive processes. The role of such coevolutionary dynamics in the continual fine-tuning of RbcL remains obscure. We used the timescale and phylogenetic analyses to investigate and search for processes of adaptive evolution in rbcL gene in three gymnosperm families, namely Podocarpaceae, Taxaceae and Cephalotaxaceae. To understand the relationships between regions identified as having evolved under adaptive evolution, we performed coevolutionary analyses using the software CAPS. Importantly, adaptive processes were identified at amino acid sites located on the contact regions among the Rubisco subunits and on the interface between Rubisco and its activase. Adaptive amino acid replacements at these regions may have optimized the holoenzyme activity. This hypothesis was pinpointed by evidence originated from our analysis of coevolution that supported the correlated evolution between Rubisco and its activase. Interestingly, the correlated adaptive processes between both these proteins have paralleled the geological variation history of the concentration of atmospheric CO2. The gene rbcL has experienced bursts of adaptations in response to the changing concentration of CO2 in the atmosphere. These adaptations have emerged as a result of a continuous dynamic of mutations, many of which may have involved innovation of functional Rubisco features. Analysis of the protein structure and the functional implications of such mutations put forward the conclusion that

  6. Brood-parasite interactions between great spotted cuckoos and magpies: a model system for studying coevolutionary relationships.

    PubMed

    Soler, Juan; Soler, Manuel

    2000-11-01

    Brood parasitism is one of the systems where coevolutionary processes have received the most research. Here, we review experiments that suggest a coevolutionary process between the great spotted cuckoo (Clamator glandarius) and its magpie (Pica pica) host. We focus on different stages of establishment of the relationship, from cuckoos selecting individual hosts and hosts defending their nests from adult cuckoos, to the ability of magpies to detect cuckoo eggs in their nests. Novel coevolutionary insights emerge from our synthesis of the literature, including how the evolution of "Mafia" behaviour in cuckoos does not necessarily inhibit the evolution of host recognition and rejection of cuckoo offspring, and how different populations of black-billed magpies in Europe have evolved specific host traits (e.g. nest and clutch size) as a result of interactions with the great spotted cuckoo. Finally, the results of the synthesis reveal the importance of using a meta-population approach when studying coevolution. This is especially relevant in those cases where gene flow among populations with different degrees of brood parasitism explains patterns of coexistence between defensive and non-defensive host phenotypes. We propose the use of a meta-population approach to distinguish between the "evolutionary equilibrium" hypothesis and the "evolutionary lag" hypothesis.

  7. Competition for finite resources

    NASA Astrophysics Data System (ADS)

    Cook, L. Jonathan; Zia, R. K. P.

    2012-05-01

    The resources in a cell are finite, which implies that the various components of the cell must compete for resources. One such resource is the ribosomes used during translation to create proteins. Motivated by this example, we explore this competition by connecting two totally asymmetric simple exclusion processes (TASEPs) to a finite pool of particles. Expanding on our previous work, we focus on the effects on the density and current of having different entry and exit rates.

  8. Effects of payoff-related velocity in the co-evolutionary snowdrift game

    NASA Astrophysics Data System (ADS)

    Yang, Zhihu; Li, Zhi; Wu, Te; Wang, Long

    2014-01-01

    Previous studies concerning mobile populations seldom distinguish mobility on the individual level. In these models, all individuals have the identical moving speed and this moving speed has not been clearly defined in terms of its relevance to other features intrinsic to individual. Here we investigate the evolution of cooperation with a minimal co-evolutionary snowdrift game in which the payoff-dependent velocity as well as velocity diversity is taken into account. We find that the fate of evolution in such scenarios is precisely ruled both by population mobility and the inherent parameter of the snowdrift game. The outside-in and inside-out like attacks on cooperator clusters (C-clusters) are triggered in the Monte Carlo simulation. The results show that low mobility can lead to a plateau of full cooperation provided the challenge to cooperate is not too high, and also that high mobility always inhibits cooperation. Nevertheless, the phase transition diagram implies moderate population mobility most benefits the survival of cooperators when cooperation faces the greater challenge. Finally, the evolution of strategies seemingly rises superior to selection strength once the mobility intensity is fixed. Our findings may shed new light on the evolution of strategies in mobile systems.

  9. Coevolutionary interactions between farmers and mafia induce host acceptance of avian brood parasites

    PubMed Central

    Hilbe, Christian; Traulsen, Arne

    2016-01-01

    Brood parasites exploit their host in order to increase their own fitness. Typically, this results in an arms race between parasite trickery and host defence. Thus, it is puzzling to observe hosts that accept parasitism without any resistance. The ‘mafia’ hypothesis suggests that these hosts accept parasitism to avoid retaliation. Retaliation has been shown to evolve when the hosts condition their response to mafia parasites, who use depredation as a targeted response to rejection. However, it is unclear if acceptance would also emerge when ‘farming’ parasites are present in the population. Farming parasites use depredation to synchronize the timing with the host, destroying mature clutches to force the host to re-nest. Herein, we develop an evolutionary model to analyse the interaction between depredatory parasites and their hosts. We show that coevolutionary cycles between farmers and mafia can still induce host acceptance of brood parasites. However, this equilibrium is unstable and in the long-run the dynamics of this host–parasite interaction exhibits strong oscillations: when farmers are the majority, accepters conditional to mafia (the host will reject first and only accept after retaliation by the parasite) have a higher fitness than unconditional accepters (the host always accepts parasitism). This leads to an increase in mafia parasites’ fitness and in turn induce an optimal environment for accepter hosts. PMID:27293783

  10. Coevolutionary interactions between farmers and mafia induce host acceptance of avian brood parasites.

    PubMed

    Abou Chakra, Maria; Hilbe, Christian; Traulsen, Arne

    2016-05-01

    Brood parasites exploit their host in order to increase their own fitness. Typically, this results in an arms race between parasite trickery and host defence. Thus, it is puzzling to observe hosts that accept parasitism without any resistance. The 'mafia' hypothesis suggests that these hosts accept parasitism to avoid retaliation. Retaliation has been shown to evolve when the hosts condition their response to mafia parasites, who use depredation as a targeted response to rejection. However, it is unclear if acceptance would also emerge when 'farming' parasites are present in the population. Farming parasites use depredation to synchronize the timing with the host, destroying mature clutches to force the host to re-nest. Herein, we develop an evolutionary model to analyse the interaction between depredatory parasites and their hosts. We show that coevolutionary cycles between farmers and mafia can still induce host acceptance of brood parasites. However, this equilibrium is unstable and in the long-run the dynamics of this host-parasite interaction exhibits strong oscillations: when farmers are the majority, accepters conditional to mafia (the host will reject first and only accept after retaliation by the parasite) have a higher fitness than unconditional accepters (the host always accepts parasitism). This leads to an increase in mafia parasites' fitness and in turn induce an optimal environment for accepter hosts.

  11. Environment Sensitivity-based Cooperative Co-evolutionary Algorithms for Dynamic Multi-objective Optimization.

    PubMed

    Xu, Biao; Zhang, Yong; Gong, Dunwei; Guo, Yinan; Rong, Miao

    2017-01-16

    Dynamic multi-objective optimization problems (DMOPs) not only involve multiple conflicting objectives, but these objectives may also vary with time, raising a challenge for researchers to solve them. This paper presents a cooperative co-evolutionary strategy based on environment sensitivities for solving DMOPs. In this strategy, a new method that groups decision variables is first proposed, in which all the decision variables are partitioned into two subcomponents according to their interrelation with environment. Adopting two populations to cooperatively optimize the two subcomponents, two prediction methods, i.e., differential prediction and Cauchy mutation, are then employed respectively to speed up their responses on the change of the environment. Furthermore, two improved dynamic multi-objective optimization algorithms, i.e., DNSGAII-CO and DMOPSO-CO, are proposed by incorporating the above strategy into NSGA-II and multi-objective particle swarm optimization, respectively. The proposed algorithms are compared with three state-of-the-art algorithms by applying to seven benchmark DMOPs. Experimental results reveal that the proposed algorithms significantly outperform the compared algorithms in terms of convergence and distribution on most DMOPs.

  12. Co-evolutionary dynamics between a defensive microbe and a pathogen driven by fluctuating selection.

    PubMed

    Ford, Suzanne A; Williams, David; Paterson, Steve; King, Kayla C

    2017-04-01

    Microbes that protect their hosts from pathogenic infection are widespread components of the microbiota of both plants and animals. It has been found that interactions between 'defensive' microbes and pathogens can be genotype-specific and even underlie the variation in host resistance to pathogenic infection. These observations suggest a dynamic co-evolutionary association between pathogens and defensive microbes, but direct evidence of co-evolution is lacking. We tested the hypothesis that defensive microbes and pathogens could co-evolve within host populations by co-passaging a microbe with host-defensive properties (Enterococcus faecalis) and a pathogen (Staphylococcus aureus) within Caenorhabditis elegans nematodes. Using both phenotypic and genomic analyses across evolutionary time, we found patterns of pathogen local adaptation and defensive microbe-pathogen co-evolution via fluctuating selection dynamics. Moreover, co-evolution with defensive microbes resulted in more rapid and divergent pathogen evolution compared to pathogens evolved independently in host populations. Taken together, our results indicate the potential for defensive microbes and pathogens to co-evolve, driving interaction specificity and pathogen evolutionary divergence in the absence of host evolution. © 2016 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  13. Cry-wolf signals emerging from coevolutionary feedbacks in a tritrophic system

    PubMed Central

    Yamauchi, Atsushi; van Baalen, Minus; Kobayashi, Yutaka; Takabayashi, Junji; Shiojiri, Kaori; Sabelis, Maurice W.

    2015-01-01

    For a communication system to be stable, senders should convey honest information. Providing dishonest information, however, can be advantageous to senders, which imposes a constraint on the evolution of communication systems. Beyond single populations and bitrophic systems, one may ask whether stable communication systems can evolve in multitrophic systems. Consider cross-species signalling where herbivore-induced plant volatiles (HIPVs) attract predators to reduce the damage from arthropod herbivores. Such plant signals may be honest and help predators to identify profitable prey/plant types via HIPV composition and to assess prey density via the amount of HIPVs. There could be selection for dishonest signals that attract predators for protection from possible future herbivory. Recently, we described a case in which plants release a fixed, high amount of HIPVs independent of herbivore load, adopting what we labelled a ‘cry-wolf’ strategy. To understand when such signals evolve, we model coevolutionary interactions between plants, herbivores and predators, and show that both ‘honest’ and ‘cry-wolf’ types can emerge, depending on the assumed plant–herbivore encounter rates and herbivore population density. It is suggested that the ‘cry-wolf’ strategy may have evolved to reduce the risk of heavy damage in the future. Our model suggests that eco-evolutionary feedback loops involving a third species may have important consequences for the stability of this outcome. PMID:26538597

  14. Coevolutionary analysis of resistance-evading peptidomimetic inhibitors of HIV-1 protease.

    PubMed

    Rosin, C D; Belew, R K; Morris, G M; Olson, A J; Goodsell, D S

    1999-02-16

    We have developed a coevolutionary method for the computational design of HIV-1 protease inhibitors selected for their ability to retain efficacy in the face of protease mutation. For HIV-1 protease, typical drug design techniques are shown to be ineffective for the design of resistance-evading inhibitors: An inhibitor that is a direct analogue of one of the natural substrates will be susceptible to resistance mutation, as will inhibitors designed to fill the active site of the wild-type or a mutant enzyme. Two design principles are demonstrated: (i) For enzymes with broad substrate specificity, such as HIV-1 protease, resistance-evading inhibitors are best designed against the immutable properties of the active site-the properties that must be conserved in any mutant protease to retain the ability to bind and cleave all of the native substrates. (ii) Robust resistance-evading inhibitors can be designed by optimizing activity simultaneously against a large set of mutant enzymes, incorporating as much of the mutational space as possible.

  15. Coevolutionary analysis of resistance-evading peptidomimetic inhibitors of HIV-1 protease

    PubMed Central

    Rosin, Christopher D.; Belew, Richard K.; Morris, Garrett M.; Olson, Arthur J.; Goodsell, David S.

    1999-01-01

    We have developed a coevolutionary method for the computational design of HIV-1 protease inhibitors selected for their ability to retain efficacy in the face of protease mutation. For HIV-1 protease, typical drug design techniques are shown to be ineffective for the design of resistance-evading inhibitors: An inhibitor that is a direct analogue of one of the natural substrates will be susceptible to resistance mutation, as will inhibitors designed to fill the active site of the wild-type or a mutant enzyme. Two design principles are demonstrated: (i) For enzymes with broad substrate specificity, such as HIV-1 protease, resistance-evading inhibitors are best designed against the immutable properties of the active site—the properties that must be conserved in any mutant protease to retain the ability to bind and cleave all of the native substrates. (ii) Robust resistance-evading inhibitors can be designed by optimizing activity simultaneously against a large set of mutant enzymes, incorporating as much of the mutational space as possible. PMID:9990030

  16. Quantitative genetic insights into the coevolutionary dynamics of male and female genitalia

    PubMed Central

    Evans, Jonathan P.; van Lieshout, Emile; Gasparini, Clelia

    2013-01-01

    The spectacular variability that typically characterizes male genital traits has largely been attributed to the role of sexual selection. Among the evolutionary mechanisms proposed to account for this diversity, two processes in particular have generated considerable interest. On the one hand, females may exploit postcopulatory mechanisms of selection to favour males with preferred genital traits (cryptic female choice; CFC), while on the other hand females may evolve structures or behaviours that mitigate the direct costs imposed by male genitalia (sexual conflict; SC). A critical but rarely explored assumption underlying both processes is that male and female reproductive traits coevolve, either via the classic Fisherian model of preference-trait coevolution (CFC) or through sexually antagonistic selection (SC). Here, we provide evidence for this prediction in the guppy (Poecilia reticulata), a polyandrous livebearing fish in which males transfer sperm internally to females via consensual and forced matings. Our results from a paternal half-sibling breeding design reveal substantial levels of additive genetic variation underlying male genital size and morphology—two traits known to predict mating success during non-consensual matings. Our subsequent finding that physically interacting female genital traits exhibit corresponding levels of genetic (co)variation reveals the potential intersexual coevolutionary dynamics of male and female genitalia, thereby fulfilling a fundamental assumption underlying CFC and SC theory. PMID:23720546

  17. Dispersal network structure and infection mechanism shape diversity in a coevolutionary bacteria-phage system.

    PubMed

    Sieber, Michael; Robb, Matthew; Forde, Samantha E; Gudelj, Ivana

    2014-03-01

    Resource availability, dispersal and infection genetics all have the potential to fundamentally alter the coevolutionary dynamics of bacteria-bacteriophage interactions. However, it remains unclear how these factors synergise to shape diversity within bacterial populations. We used a combination of laboratory experiments and mathematical modeling to test how the structure of a dispersal network affects host phenotypic diversity in a coevolving bacteria-phage system in communities of differential resource input. Unidirectional dispersal of bacteria and phage from high to low resources consistently increased host diversity compared with a no dispersal regime. Bidirectional dispersal, on the other hand, led to a marked decrease in host diversity. Our mathematical model predicted these opposing outcomes when we incorporated modified gene-for-gene infection genetics. To further test how host diversity depended on the genetic underpinnings of the bacteria-phage interaction, we expanded our mathematical model to include different infection mechanisms. We found that the direction of dispersal had very little impact on bacterial diversity when the bacteria-phage interaction was mediated by matching alleles, gene-for-gene or related infection mechanisms. Our experimental and theoretical results demonstrate that the effects of dispersal on diversity in coevolving host-parasite systems depend on an intricate interplay of the structure of the underlying dispersal network and the specifics of the host-parasite interaction.

  18. Quantitative genetic insights into the coevolutionary dynamics of male and female genitalia.

    PubMed

    Evans, Jonathan P; van Lieshout, Emile; Gasparini, Clelia

    2013-07-22

    The spectacular variability that typically characterizes male genital traits has largely been attributed to the role of sexual selection. Among the evolutionary mechanisms proposed to account for this diversity, two processes in particular have generated considerable interest. On the one hand, females may exploit postcopulatory mechanisms of selection to favour males with preferred genital traits (cryptic female choice; CFC), while on the other hand females may evolve structures or behaviours that mitigate the direct costs imposed by male genitalia (sexual conflict; SC). A critical but rarely explored assumption underlying both processes is that male and female reproductive traits coevolve, either via the classic Fisherian model of preference-trait coevolution (CFC) or through sexually antagonistic selection (SC). Here, we provide evidence for this prediction in the guppy (Poecilia reticulata), a polyandrous livebearing fish in which males transfer sperm internally to females via consensual and forced matings. Our results from a paternal half-sibling breeding design reveal substantial levels of additive genetic variation underlying male genital size and morphology-two traits known to predict mating success during non-consensual matings. Our subsequent finding that physically interacting female genital traits exhibit corresponding levels of genetic (co)variation reveals the potential intersexual coevolutionary dynamics of male and female genitalia, thereby fulfilling a fundamental assumption underlying CFC and SC theory.

  19. Cry-wolf signals emerging from coevolutionary feedbacks in a tritrophic system.

    PubMed

    Yamauchi, Atsushi; van Baalen, Minus; Kobayashi, Yutaka; Takabayashi, Junji; Shiojiri, Kaori; Sabelis, Maurice W

    2015-11-07

    For a communication system to be stable, senders should convey honest information. Providing dishonest information, however, can be advantageous to senders, which imposes a constraint on the evolution of communication systems. Beyond single populations and bitrophic systems, one may ask whether stable communication systems can evolve in multitrophic systems. Consider cross-species signalling where herbivore-induced plant volatiles (HIPVs) attract predators to reduce the damage from arthropod herbivores. Such plant signals may be honest and help predators to identify profitable prey/plant types via HIPV composition and to assess prey density via the amount of HIPVs. There could be selection for dishonest signals that attract predators for protection from possible future herbivory. Recently, we described a case in which plants release a fixed, high amount of HIPVs independent of herbivore load, adopting what we labelled a 'cry-wolf' strategy. To understand when such signals evolve, we model coevolutionary interactions between plants, herbivores and predators, and show that both 'honest' and 'cry-wolf' types can emerge, depending on the assumed plant-herbivore encounter rates and herbivore population density. It is suggested that the 'cry-wolf' strategy may have evolved to reduce the risk of heavy damage in the future. Our model suggests that eco-evolutionary feedback loops involving a third species may have important consequences for the stability of this outcome.

  20. Comparative dating of attine ant and lepiotaceous cultivar phylogenies reveals coevolutionary synchrony and discord.

    PubMed

    Mikheyev, Alexander S; Mueller, Ulrich G; Abbot, Patrick

    2010-06-01

    The mutualistic symbiosis between fungus-gardening ants and their cultivars has made fundamental contributions to our understanding of the coevolution of complex species interactions. Reciprocal specialization and vertical symbiont cotransmission are thought to promote a pattern of largely synchronous coevolutionary diversification in attines. Here we test this hypothesis by inferring the first time-calibrated multigene phylogeny of the lepiotaceous attine cultivars and comparing it with the recently published fossil-anchored phylogeny of the attine ants. While this comparison reveals some possible cases of synchronous origins of ant and fungal clades, there were a number of surprising asynchronies. For example, leaf-cutter cultivars appear to be significantly younger than the corresponding ant genera. Similarly, a clade of fungi interacting with primitive fungus-gardening ants--thought to be ancestral to the more derived leaf-cutter symbionts--appears instead to be a more recent acquisition from free-living stock. These macroevolutionary patterns are consistent with recent population-level studies suggesting occasional acquisition of novel cultivar types from environmental sources and horizontal transmission of cultivars between different ant species. Horizontal transmission events, even if rare, appear to form loose ecological connections between diffusely coevolving ant and fungus lineages that permit punctuated changes in the topology of the mutualistic ant-fungus interaction network.

  1. Testing co-evolutionary hypotheses over geological timescales: interactions between Mesozoic non-avian dinosaurs and cycads.

    PubMed

    Butler, Richard J; Barrett, Paul M; Kenrick, Paul; Penn, Malcolm G

    2009-02-01

    The significance of co-evolution over ecological timescales is well established, yet it remains unclear to what extent co-evolutionary processes contribute to driving large-scale evolutionary and ecological changes over geological timescales. Some of the most intriguing and pervasive long-term co-evolutionary hypotheses relate to proposed interactions between herbivorous non-avian dinosaurs and Mesozoic plants, including cycads. Dinosaurs have been proposed as key dispersers of cycad seeds during the Mesozoic, and temporal variation in cycad diversity and abundance has been linked to dinosaur faunal changes. Here we assess the evidence for proposed hypotheses of trophic and evolutionary interactions between these two groups using diversity analyses, a new database of Cretaceous dinosaur and plant co-occurrence data, and a geographical information system (GIS) as a visualisation tool. Phylogenetic evidence suggests that the origins of several key biological properties of cycads (e.g. toxins, bright-coloured seeds) likely predated the origin of dinosaurs. Direct evidence of dinosaur-cycad interactions is lacking, but evidence from extant ecosystems suggests that dinosaurs may plausibly have acted as seed dispersers for cycads, although it is likely that other vertebrate groups (e.g. birds, early mammals) also played a role. Although the Late Triassic radiations of dinosaurs and cycads appear to have been approximately contemporaneous, few significant changes in dinosaur faunas coincide with the late Early Cretaceous cycad decline. No significant spatiotemporal associations between particular dinosaur groups and cycads can be identified - GIS visualisation reveals disparities between the spatiotemporal distributions of some dinosaur groups (e.g. sauropodomorphs) and cycads that are inconsistent with co-evolutionary hypotheses. The available data provide no unequivocal support for any of the proposed co-evolutionary interactions between cycads and herbivorous dinosaurs

  2. 48 CFR 6.204 - Section 8(a) competition.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false Section 8(a) competition... ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 6.204 Section 8(a) competition. (a) To fulfill statutory requirements relating to section 8(a) of the...

  3. 48 CFR 6.204 - Section 8(a) competition.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false Section 8(a) competition... ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 6.204 Section 8(a) competition. (a) To fulfill statutory requirements relating to section 8(a) of the...

  4. 48 CFR 6.204 - Section 8(a) competition.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Section 8(a) competition... ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 6.204 Section 8(a) competition. (a) To fulfill statutory requirements relating to section 8(a) of the...

  5. 48 CFR 6.204 - Section 8(a) competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Section 8(a) competition... ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 6.204 Section 8(a) competition. (a) To fulfill statutory requirements relating to section 8(a) of the...

  6. 40 CFR 89.611 - Exemptions and exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... sufficiently organized, EPA notifies the importer of any areas of inadequacy, and that the documentation does..., 89.609, or 89.611(c)(3). (e) Competition exclusion. A nonconforming engine may be imported by any... vehicle used solely for competition and obtains prior written approval from the Administrator....

  7. DISE: directed sphere exclusion.

    PubMed

    Gobbi, Alberto; Lee, Man-Ling

    2003-01-01

    The Sphere Exclusion algorithm is a well-known algorithm used to select diverse subsets from chemical-compound libraries or collections. It can be applied with any given distance measure between two structures. It is popular because of the intuitive geometrical interpretation of the method and its good performance on large data sets. This paper describes Directed Sphere Exclusion (DISE), a modification of the Sphere Exclusion algorithm, which retains all positive properties of the Sphere Exclusion algorithm but generates a more even distribution of the selected compounds in the chemical space. In addition, the computational requirement is significantly reduced, thus it can be applied to very large data sets.

  8. Competitive Intelligence.

    ERIC Educational Resources Information Center

    Bergeron, Pierrette; Hiller, Christine A.

    2002-01-01

    Reviews the evolution of competitive intelligence since 1994, including terminology and definitions and analytical techniques. Addresses the issue of ethics; explores how information technology supports the competitive intelligence process; and discusses education and training opportunities for competitive intelligence, including core competencies…

  9. Biological invasions and host-parasite coevolution: different coevolutionary trajectories along separate parasite invasion fronts.

    PubMed

    Feis, Marieke E; Goedknegt, M Anouk; Thieltges, David W; Buschbaum, Christian; Wegner, K Mathias

    2016-08-01

    Host-parasite coevolution has rarely been observed in natural systems. Its study often relies on microparasitic infections introducing a potential bias in the estimation of the evolutionary change of host and parasite traits. Using biological invasions as a tool to study host-parasite coevolution in nature can overcome these biases. We demonstrate this with a cross-infection experiment in the invasive macroparasite Mytilicola intestinalis and its bivalve host, the blue mussel Mytilus edulis. The invasion history of the parasite is well known for the southeastern North Sea and is characterised by two separate invasion fronts that reached opposite ends of the Wadden Sea (i.e. Texel, The Netherlands and Sylt, Germany) in a similar time frame. The species' natural history thus makes this invasion an ideal natural experiment to study host-parasite coevolution in nature. We infected hosts from Texel, Sylt and Kiel (Baltic Sea, where the parasite is absent) with parasites from Texel and Sylt, to form sympatric, allopatric and naïve infestation combinations, respectively. We measured infection rate, host condition and parasite growth to show that sympatric host-parasite combinations diverged in terms of pre- and post-infection traits within <100 generations since their introduction. Texel parasites were more infective and more efficient at exploiting the host's resources. Hosts on Texel, on the other hand, evolved resistance to infection, whereas hosts on Sylt may have evolved tolerance. This illustrates that different coevolutionary trajectories can evolve along separate invasion fronts of the parasite, highlighting the use of biological invasions in studies of host-parasite coevolution in nature.

  10. Community interactions govern host-switching with implications for host–parasite coevolutionary history

    PubMed Central

    Harbison, Christopher W.; Clayton, Dale H.

    2011-01-01

    Reciprocal selective effects between coevolving species are often influenced by interactions with the broader ecological community. Community-level interactions may also influence macroevolutionary patterns of coevolution, such as cospeciation, but this hypothesis has received little attention. We studied two groups of ecologically similar feather lice (Phthiraptera: Ischnocera) that differ in their patterns of association with a single group of hosts. The two groups, “body lice” and “wing lice,” are both parasites of pigeons and doves (Columbiformes). Body lice are more host-specific and show greater population genetic structure than wing lice. The macroevolutionary history of body lice also parallels that of their columbiform hosts more closely than does the evolutionary history of wing lice. The closer association of body lice with hosts, compared with wing lice, can be explained if body lice are less capable of switching hosts than wing lice. Wing lice sometimes disperse phoretically on parasitic flies (Diptera: Hippoboscidae), but body lice seldom engage in this behavior. We tested the hypothesis that wing lice switch host species more often than body lice, and that the difference is governed by phoresis. Our results show that, where flies are present, wing lice switch to novel host species in sufficient numbers to establish viable populations on the new host. Body lice do not switch hosts, even where flies are present. Thus, differences in the coevolutionary history of wing and body lice can be explained by differences in host-switching, mediated by a member of the broader parasite community. PMID:21606369

  11. A Molecular and Co-Evolutionary Context for Grazer Induced Toxin Production in Alexandrium tamarense

    PubMed Central

    Wohlrab, Sylke; Iversen, Morten H.; John, Uwe

    2010-01-01

    Marine dinoflagellates of the genus Alexandrium are the proximal source of neurotoxins associated with Paralytic Shellfish Poisoning. The production of these toxins, the toxin biosynthesis and, thus, the cellular toxicity can be influenced by abiotic and biotic factors. There is, however, a lack of substantial evidence concerning the toxins' ecological function such as grazing defense. Waterborne cues from copepods have been previously found to induce a species-specific increase in toxin content in Alexandrium minutum. However, it remains speculative in which context these species-specific responses evolved and if it occurs in other Alexandrium species as well. In this study we exposed Alexandrium tamarense to three copepod species (Calanus helgolandicus, Acartia clausii, and Oithona similis) and their corresponding cues. We show that the species-specific response towards copepod-cues is not restricted to one Alexandrium species and that co-evolutionary processes might be involved in these responses, thus giving additional evidence for the defensive role of phycotoxins. Through a functional genomic approach we gained insights into the underlying molecular processes which could trigger the different outcomes of these species-specific responses and consequently lead to increased toxin content in Alexandrium tamarense. We propose that the regulation of serine/threonine kinase signaling pathways has a major influence in directing the external stimuli i.e. copepod-cues, into different intracellular cascades and networks in A. tamarense. Our results show that A. tamarense can sense potential predating copepods and respond to the received information by increasing its toxin production. Furthermore, we demonstrate how a functional genomic approach can be used to investigate species interactions within the plankton community. PMID:21124775

  12. A molecular and co-evolutionary context for grazer induced toxin production in Alexandrium tamarense.

    PubMed

    Wohlrab, Sylke; Iversen, Morten H; John, Uwe

    2010-11-29

    Marine dinoflagellates of the genus Alexandrium are the proximal source of neurotoxins associated with Paralytic Shellfish Poisoning. The production of these toxins, the toxin biosynthesis and, thus, the cellular toxicity can be influenced by abiotic and biotic factors. There is, however, a lack of substantial evidence concerning the toxins' ecological function such as grazing defense. Waterborne cues from copepods have been previously found to induce a species-specific increase in toxin content in Alexandrium minutum. However, it remains speculative in which context these species-specific responses evolved and if it occurs in other Alexandrium species as well. In this study we exposed Alexandrium tamarense to three copepod species (Calanus helgolandicus, Acartia clausii, and Oithona similis) and their corresponding cues. We show that the species-specific response towards copepod-cues is not restricted to one Alexandrium species and that co-evolutionary processes might be involved in these responses, thus giving additional evidence for the defensive role of phycotoxins. Through a functional genomic approach we gained insights into the underlying molecular processes which could trigger the different outcomes of these species-specific responses and consequently lead to increased toxin content in Alexandrium tamarense. We propose that the regulation of serine/threonine kinase signaling pathways has a major influence in directing the external stimuli i.e. copepod-cues, into different intracellular cascades and networks in A. tamarense. Our results show that A. tamarense can sense potential predating copepods and respond to the received information by increasing its toxin production. Furthermore, we demonstrate how a functional genomic approach can be used to investigate species interactions within the plankton community.

  13. Sperm competition risk generates phenotypic plasticity in ovum fertilizability

    PubMed Central

    Firman, Renée C.; Simmons, Leigh W.

    2013-01-01

    Theory predicts that sperm competition will generate sexual conflict that favours increased ovum defences against polyspermy. A recent study on house mice has shown that ovum resistance to fertilization coevolves in response to increased sperm fertilizing capacity. However, the capacity for the female gamete to adjust its fertilizability as a strategic response to sperm competition risk has never, to our knowledge, been studied. We sourced house mice (Mus domesticus) from natural populations that differ in the level of sperm competition and sperm fertilizing capacity, and manipulated the social experience of females during their sexual development to simulate conditions of either a future ‘risk’ or ‘no risk’ of sperm competition. Consistent with coevolutionary predictions, we found lower fertilization rates in ova produced by females from a high sperm competition population compared with ova from a low sperm competition population, indicating that these populations are divergent in the fertilizability of their ova. More importantly, females exposed to a ‘risk’ of sperm competition produced ova that had greater resistance to fertilization than ova produced by females reared in an environment with ‘no risk’. Consequently, we show that variation in sperm competition risk during development generates phenotypic plasticity in ova fertilizability, which allows females to prepare for prevailing conditions during their reproductive life. PMID:24132308

  14. Sperm competition risk generates phenotypic plasticity in ovum fertilizability.

    PubMed

    Firman, Renée C; Simmons, Leigh W

    2013-12-07

    Theory predicts that sperm competition will generate sexual conflict that favours increased ovum defences against polyspermy. A recent study on house mice has shown that ovum resistance to fertilization coevolves in response to increased sperm fertilizing capacity. However, the capacity for the female gamete to adjust its fertilizability as a strategic response to sperm competition risk has never, to our knowledge, been studied. We sourced house mice (Mus domesticus) from natural populations that differ in the level of sperm competition and sperm fertilizing capacity, and manipulated the social experience of females during their sexual development to simulate conditions of either a future 'risk' or 'no risk' of sperm competition. Consistent with coevolutionary predictions, we found lower fertilization rates in ova produced by females from a high sperm competition population compared with ova from a low sperm competition population, indicating that these populations are divergent in the fertilizability of their ova. More importantly, females exposed to a 'risk' of sperm competition produced ova that had greater resistance to fertilization than ova produced by females reared in an environment with 'no risk'. Consequently, we show that variation in sperm competition risk during development generates phenotypic plasticity in ova fertilizability, which allows females to prepare for prevailing conditions during their reproductive life.

  15. Central Exclusive Dijet Production

    SciTech Connect

    Dechambre, A.; Cudell, J. R.; Ivanov, I. P.; Hernandez, O.

    2008-08-29

    The ingredients of central exclusive production cross section include large perturbative corrections and soft quantities that must be parametrized and fitted to data. In this talk, we summarize the results of a study of the uncertainties coming from these ingredients, in the case of exclusive dijet production.

  16. Why is entry exclusion an essential feature of conjugative plasmids?

    PubMed

    Garcillán-Barcia, M Pilar; de la Cruz, Fernando

    2008-07-01

    Entry exclusion is a property of plasmids by which the cells that contain them become bad recipients in additional conjugation rounds. This work reviews entry exclusion essential features and analyzes the mechanisms of action of the best studied systems. We searched for homologs of the proteins responsible for experimentally known exclusion systems. Results were used to classify exclusion systems in families of related elements. We arrive to the conclusion that all conjugative plasmids contain at least one entry exclusion gene. Although entry exclusion genes seem to be part of the plasmid conjugative machinery, they are systematically absent in phylogenetically related type IV protein exporting machines involved in virulence for plants and animals. We infer from this fact that entry exclusion is an essential feature of conjugative plasmid biology. Mathematical models suggest that plasmids expressing entry exclusion selectively eliminate plasmids lacking it, reinforcing its essential character and suggesting that entry exclusion plays a direct role in plasmid survival. Other experimental results confirm that entry exclusion is essential for the stability of a conjugative plasmid. We suggest that entry exclusion limits the damage of lethal zygosis (bacterial death produced by excessive rounds of conjugation). Additionally, it avoids competition in a host among identical plasmid backbones. Conversely, the lack of entry exclusion in conjugative transposons can be understood as a means of generating rapid evolutionary change.

  17. A Coevolutionary Residue Network at the Site of a Functionally Important Conformational Change in a Phosphohexomutase Enzyme Family

    PubMed Central

    Furdui, Cristina; Beamer, Lesa J.

    2012-01-01

    Coevolution analyses identify residues that co-vary with each other during evolution, revealing sequence relationships unobservable from traditional multiple sequence alignments. Here we describe a coevolutionary analysis of phosphomannomutase/phosphoglucomutase (PMM/PGM), a widespread and diverse enzyme family involved in carbohydrate biosynthesis. Mutual information and graph theory were utilized to identify a network of highly connected residues with high significance. An examination of the most tightly connected regions of the coevolutionary network reveals that most of the involved residues are localized near an interdomain interface of this enzyme, known to be the site of a functionally important conformational change. The roles of four interface residues found in this network were examined via site-directed mutagenesis and kinetic characterization. For three of these residues, mutation to alanine reduces enzyme specificity to ∼10% or less of wild-type, while the other has ∼45% activity of wild-type enzyme. An additional mutant of an interface residue that is not densely connected in the coevolutionary network was also characterized, and shows no change in activity relative to wild-type enzyme. The results of these studies are interpreted in the context of structural and functional data on PMM/PGM. Together, they demonstrate that a network of coevolving residues links the highly conserved active site with the interdomain conformational change necessary for the multi-step catalytic reaction. This work adds to our understanding of the functional roles of coevolving residue networks, and has implications for the definition of catalytically important residues. PMID:22685552

  18. Mutually Exclusive Uncertainty Relations

    PubMed Central

    Xiao, Yunlong; Jing, Naihuan

    2016-01-01

    The uncertainty principle is one of the characteristic properties of quantum theory based on incompatibility. Apart from the incompatible relation of quantum states, mutually exclusiveness is another remarkable phenomenon in the information- theoretic foundation of quantum theory. We investigate the role of mutual exclusive physical states in the recent work of stronger uncertainty relations for all incompatible observables by Mccone and Pati and generalize the weighted uncertainty relation to the product form as well as their multi-observable analogues. The new bounds capture both incompatibility and mutually exclusiveness, and are tighter compared with the existing bounds. PMID:27824161

  19. Mutually Exclusive Uncertainty Relations.

    PubMed

    Xiao, Yunlong; Jing, Naihuan

    2016-11-08

    The uncertainty principle is one of the characteristic properties of quantum theory based on incompatibility. Apart from the incompatible relation of quantum states, mutually exclusiveness is another remarkable phenomenon in the information- theoretic foundation of quantum theory. We investigate the role of mutual exclusive physical states in the recent work of stronger uncertainty relations for all incompatible observables by Mccone and Pati and generalize the weighted uncertainty relation to the product form as well as their multi-observable analogues. The new bounds capture both incompatibility and mutually exclusiveness, and are tighter compared with the existing bounds.

  20. Mutually Exclusive Uncertainty Relations

    NASA Astrophysics Data System (ADS)

    Xiao, Yunlong; Jing, Naihuan

    2016-11-01

    The uncertainty principle is one of the characteristic properties of quantum theory based on incompatibility. Apart from the incompatible relation of quantum states, mutually exclusiveness is another remarkable phenomenon in the information- theoretic foundation of quantum theory. We investigate the role of mutual exclusive physical states in the recent work of stronger uncertainty relations for all incompatible observables by Mccone and Pati and generalize the weighted uncertainty relation to the product form as well as their multi-observable analogues. The new bounds capture both incompatibility and mutually exclusiveness, and are tighter compared with the existing bounds.

  1. Phylogenetic diversity and co-evolutionary signals among trophic levels change across a habitat edge.

    PubMed

    Peralta, Guadalupe; Frost, Carol M; Didham, Raphael K; Varsani, Arvind; Tylianakis, Jason M

    2015-03-01

    Incorporating the evolutionary history of species into community ecology enhances understanding of community composition, ecosystem functioning and responses to environmental changes. Phylogenetic history might partly explain the impact of fragmentation and land-use change on assemblages of interacting organisms and even determine potential cascading effects across trophic levels. However, it remains unclear whether phylogenetic diversity of basal resources is reflected at higher trophic levels in the food web. In particular, phylogenetic determinants of community structure have never been incorporated into habitat edge studies, even though edges are recognized as key factors affecting communities in fragmented landscapes. Here, we test whether phylogenetic diversity at different trophic levels (plants, herbivores and parasitoids) and signals of co-evolution (i.e. phylogenetic congruence) among interacting trophic levels change across an edge gradient between native and plantation forests. To ascertain whether there is a signal of co-evolution across trophic levels, we test whether related consumer species generally feed on related resource species. We found differences across trophic levels in how their phylogenetic diversity responded to the habitat edge gradient. Plant and native parasitoid phylogenetic diversity changed markedly across habitats, while phylogenetic variability of herbivores (which were predominantly native) did not change across habitats, though phylogenetic evenness declined in plantation interiors. Related herbivore species did not appear to feed disproportionately on related plant species (i.e. there was no signal of co-evolution) even when considering only native species, potentially due to the high trophic generality of herbivores. However, related native parasitoid species tended to feed on related herbivore species, suggesting the presence of a co-evolutionary signal at higher trophic levels. Moreover, this signal was stronger in

  2. Coevolutionary modeling of protein sequences: Predicting structure, function, and mutational landscapes

    NASA Astrophysics Data System (ADS)

    Weigt, Martin

    Over the last years, biological research has been revolutionized by experimental high-throughput techniques, in particular by next-generation sequencing technology. Unprecedented amounts of data are accumulating, and there is a growing request for computational methods unveiling the information hidden in raw data, thereby increasing our understanding of complex biological systems. Statistical-physics models based on the maximum-entropy principle have, in the last few years, played an important role in this context. To give a specific example, proteins and many non-coding RNA show a remarkable degree of structural and functional conservation in the course of evolution, despite a large variability in amino acid sequences. We have developed a statistical-mechanics inspired inference approach - called Direct-Coupling Analysis - to link this sequence variability (easy to observe in sequence alignments, which are available in public sequence databases) to bio-molecular structure and function. In my presentation I will show, how this methodology can be used (i) to infer contacts between residues and thus to guide tertiary and quaternary protein structure prediction and RNA structure prediction, (ii) to discriminate interacting from non-interacting protein families, and thus to infer conserved protein-protein interaction networks, and (iii) to reconstruct mutational landscapes and thus to predict the phenotypic effect of mutations. References [1] M. Figliuzzi, H. Jacquier, A. Schug, O. Tenaillon and M. Weigt ''Coevolutionary landscape inference and the context-dependence of mutations in beta-lactamase TEM-1'', Mol. Biol. Evol. (2015), doi: 10.1093/molbev/msv211 [2] E. De Leonardis, B. Lutz, S. Ratz, S. Cocco, R. Monasson, A. Schug, M. Weigt ''Direct-Coupling Analysis of nucleotide coevolution facilitates RNA secondary and tertiary structure prediction'', Nucleic Acids Research (2015), doi: 10.1093/nar/gkv932 [3] F. Morcos, A. Pagnani, B. Lunt, A. Bertolino, D. Marks, C

  3. Information use and resource competition: an integrative framework

    PubMed Central

    Ounsley, James P.

    2016-01-01

    Organisms may reduce uncertainty regarding how best to exploit their environment by collecting information about resource distribution. We develop a model to demonstrate how competition can facilitate or constrain an individual's ability to use information when acquiring resources. As resource distribution underpins both selection on information use and the strength and nature of competition between individuals, we demonstrate interdependencies between the two that should be common in nature. Individuals in our model can search for resources either personally or by using social information. We explore selection on social information use across a comprehensive range of ecological conditions, generalizing the producer–scrounger framework to a wide diversity of taxa and resources. We show that resource ecology—defined by scarcity, depletion rate and monopolizability—determines patterns of individual differences in social information use. These differences suggest coevolutionary processes linking dominance systems and social information use, with implications for the evolutionary demography of populations. PMID:26888031

  4. Friendly competition.

    PubMed

    Chambers, David W

    2006-01-01

    Competition that is characterized by rules, often informal, agreed among mutually accepted participants, and that gives the competitors a special, advantageous status with others is called friendly competition. Dentists have engaged in it deeply and it is good for the profession. Friendly competition offers the advantages of spillover of commonly useful information and technologies, stimulation of innovation, a united and convenient face to customers and suppliers, and standards that promote growth. Friendly competition increases the size of the pie, regardless of market share. Paradoxically, this is even true for the little guy in the shadow of the giant. If carried to extremes, unfriendly competition leads to destroying competitors, the confusion of multiple rules, and encouragement of disruptive change.

  5. UK Higher Education: Competitive Forces in the 21st Century.

    ERIC Educational Resources Information Center

    Webber, G. C.

    2000-01-01

    Considers United Kingdom higher education in the context of Michael Porter's book, "Competitive Strategy," which discusses five forces governing competition. Focusing mainly, but not exclusively, on teaching, the monograph identifies critical factors that have influenced the balance of competitive forces in higher education and…

  6. UK Higher Education: Competitive Forces in the 21st Century.

    ERIC Educational Resources Information Center

    Webber, G. C.

    2000-01-01

    Considers United Kingdom higher education in the context of Michael Porter's book, "Competitive Strategy," which discusses five forces governing competition. Focusing mainly, but not exclusively, on teaching, the monograph identifies critical factors that have influenced the balance of competitive forces in higher education and…

  7. 48 CFR 6.204 - Section 8(a) competition.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Section 8(a) competition. 6.204 Section 6.204 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION ACQUISITION PLANNING COMPETITION REQUIREMENTS Full and Open Competition After Exclusion of Sources 6.204...

  8. Exclusive production at CMS

    NASA Astrophysics Data System (ADS)

    Khakzad, Mohsen

    2017-03-01

    A search for exclusive or quasi-exclusive γγ → W+W- production, pp → p(∗)W+W-p(∗) → p(∗)μ±e∓p(∗), at √{s }=8 TeV (7 TeV) is reported using data corresponding to an integrated luminosity of 19.7 fb-1 (5.5fb-1), respectively. In this study, we look for any deviations that there might be from the Standard Model, and the results are used to set limits on the Anomalous Quartic Gauge Couplings. We also report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions. The differential cross sections for π+π- pairs as a function of the pion pair invariant mass is measured and compared to several phenomenological predictions.

  9. Mutually Exclusive, Complementary, or . . .

    ERIC Educational Resources Information Center

    Schloemer, Cathy G.

    2016-01-01

    Whether students are beginning their study of probability or are well into it, distinctions between complementary sets and mutually exclusive sets can be confusing. Cathy Schloemer writes in this article that for years she used typical classroom examples but was not happy with the student engagement or the level of understanding they produced.…

  10. Mutually Exclusive, Complementary, or . . .

    ERIC Educational Resources Information Center

    Schloemer, Cathy G.

    2016-01-01

    Whether students are beginning their study of probability or are well into it, distinctions between complementary sets and mutually exclusive sets can be confusing. Cathy Schloemer writes in this article that for years she used typical classroom examples but was not happy with the student engagement or the level of understanding they produced.…

  11. Reproductive interference determines persistence and exclusion in species interactions.

    PubMed

    Kishi, Shigeki; Nishida, Takayoshi; Tsubaki, Yoshitaka

    2009-09-01

    1. Reproductive interference is a negative interspecific sexual interaction that adversely affects the fitness of males and females during reproductive process. Theoretical studies suggest that because reproductive interference is characterized by positive frequency dependence it is far more likely to cause species exclusion than the density dependence of resource competition. However, the respective contributions of resource competition and reproductive interference to species exclusion, which have been frequently observed in many competition studies, remain unclear. 2. We show that reproductive interference is a far more critical cause of species exclusion than resource competition in the competition between Callosobruchus bean weevil species. In competition experiments over several generations, we manipulated the initial relative abundance of the adzuki bean beetle, Callosobruchus chinensis, and the southern cowpea beetle, Callosobruchus maculatus. When the initial adult ratio of C. chinensis : C. maculatus were 6 : 2 and 4 : 4, C. chinensis excluded C. maculatus. However, when C. maculatus was four times more abundant than C. chinensis at the start, we observed the opposite outcome. 3. A behavioural experiment using adults of the two species revealed asymmetric reproductive interference. The fecundity and longevity of C. maculatus females, but not those of C. chinensis females, decreased when the females were kept with heterospecific males. Fecundities of females of both species decreased as the number of heterospecific males increased. In contrast, resource competition at the larval stage resulted in higher survival of C. maculatus than of C. chinensis. 4. These results suggest that the positive frequency-dependent effect of reproductive interference resulted in species exclusion, depending on the initial population ratio of the two species, and the asymmetry of the interference resulted in C. chinensis being dominant in this study, as in previous studies

  12. "Excellence" and Exclusion: The Individual Costs of Institutional Competitiveness

    ERIC Educational Resources Information Center

    Watermeyer, Richard; Olssen, Mark

    2016-01-01

    A performance-based funding system like the United Kingdom's "Research Excellence Framework" (REF) symbolizes the re-rationalization of higher education according to neoliberal ideology and New Public Management technologies. The REF is also significant for disclosing the kinds of behaviour that characterize universities' response to…

  13. "Excellence" and Exclusion: The Individual Costs of Institutional Competitiveness

    ERIC Educational Resources Information Center

    Watermeyer, Richard; Olssen, Mark

    2016-01-01

    A performance-based funding system like the United Kingdom's "Research Excellence Framework" (REF) symbolizes the re-rationalization of higher education according to neoliberal ideology and New Public Management technologies. The REF is also significant for disclosing the kinds of behaviour that characterize universities' response to…

  14. Probiotics, prebiotics, and competitive exclusion for prophylaxis against bacterial disease

    USDA-ARS?s Scientific Manuscript database

    Bacteria that are pathogenic to animals and human consumers can exist in the gastrointestinal tract of our food animal species. The gastrointestinal tract of food animals can be inhabited by bacteria that cause foodborne illnesses in humans, but that do not cause detectable animal illnesses or a de...

  15. Type III effector diversification via both pathoadaptation and horizontal transfer in response to a coevolutionary arms race.

    PubMed

    Ma, Wenbo; Dong, Frederick F T; Stavrinides, John; Guttman, David S

    2006-12-01

    The concept of the coevolutionary arms race holds a central position in our understanding of pathogen-host interactions. Here we identify the molecular mechanisms and follow the stepwise progression of an arms race in a natural system. We show how the evolution and function of the HopZ family of type III secreted effector proteins carried by the plant pathogen Pseudomonas syringae are influenced by a coevolutionary arms race between pathogen and host. We surveyed 96 isolates of P. syringae and identified three homologs (HopZ1, HopZ2, and HopZ3) distributed among approximately 45% of the strains. All alleles were sequenced and their expression was confirmed. Evolutionary analyses determined that the diverse HopZ1 homologs are ancestral to P. syringae, and have diverged via pathoadaptive mutational changes into three functional and two degenerate forms, while HopZ2 and HopZ3 have been brought into P. syringae via horizontal transfer from other ecologically similar bacteria. A PAML selection analysis revealed that the C terminus of HopZ1 is under strong positive selection. Despite the extensive genetic variation observed in this family, all three homologs have cysteine-protease activity, although their substrate specificity may vary. The introduction of the ancestral hopZ1 allele into strains harboring alternate alleles results in a resistance protein-mediated defense response in their respective hosts, which is not observed with the endogenous allele. These data indicate that the P. syringae HopZ family has undergone allelic diversification via both pathoadaptive mutational changes and horizontal transfer in response to selection imposed by the host defense system. This genetic diversity permits the pathogen to avoid host defenses while still maintaining a virulence-associated protease, thereby allowing it to thrive on its current host, while simultaneously impacting its host range.

  16. 47 CFR 22.201 - Paging geographic area authorizations are subject to competitive bidding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Licensing Requirements and Procedures Competitive.... Mutually exclusive initial applications for paging geographic area licenses are subject to...

  17. 47 CFR 22.969 - Cellular RSA licenses subject to competitive bidding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CARRIER SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.969 Cellular RSA licenses subject to competitive bidding. Mutually exclusive applications for initial authorization for...

  18. Tough Competition.

    ERIC Educational Resources Information Center

    King, Roland

    1994-01-01

    College and university public relations specialists find that, to get competitive coverage for their institutions, they must provide the media with instant access to information and understand the way the media operate. Although the computer is useful in expanding contacts, responsiveness and information of real interest are foremost…

  19. EDITORIAL: Physics competitions Physics competitions

    NASA Astrophysics Data System (ADS)

    Jordens, H.; Mathelitsch, L.

    2009-11-01

    1. Physics competitions: aims and realizations One aim of physics competitions is to increase the interest of young students, primarily at upper secondary level, to physics and natural sciences in general. A competition has motivational aspects known usually from sports events or games—comparing one's own ability with others, of course with the desire to be better and to win. If competitions reach nationwide and even international levels, additional stimulation is created. Competitions provide greatest attraction to possible winners, to the group of gifted people in a particular field. This implies that science contests are excellent tools for the promotion of talented students. Traditional teaching has been shown to have problems in supporting this group of students. Very often teachers are overstretched with the demands of teaching both low- and high-level students. Extracurricular activities are therefore a good chance to relieve the teacher, and to give talented students the opportunity for appropriate training and challenge. The competitions, however, have a broader impact and address more young people than one might guess from the statements above. Training courses and selection at school level give a larger group of students extra and, to some extent, complimentary education in physics. The degree of complexity of the tasks corresponds very often to the standards of the next level of education in the school system. Interestingly, many physics competitions have their origin in countries beyond the former Iron Curtain. They started as regional and national tournaments, were joined by neighbouring countries and have grown, in some cases, to events with participants from more than 80 countries. Although the features mentioned above are common to the different competitions, there are distinct differences between them [1]. The International Physics Olympiad (IPhO) is the oldest international physics competition for students at upper secondary level [2]. It dates

  20. Coevolutionary dynamics of networks and games under birth-death and birth mechanisms

    NASA Astrophysics Data System (ADS)

    Huang, Z.-G.; Wu, Z.-X.; Xu, X.-J.; Guan, J.-Y.; Wang, Y.-H.

    2007-08-01

    There is much interest in studying evolutionary games in structured populations, in order to understand how cooperation emerges in communities of egoistic agents. In this paper, we consider a new mechanism for cooperation to survive on networks. Agents are designed to reproduce offspring in proportion to their fitness, i.e., the aggregate payoffs they collected in the previous Prisoner's Dilemma game with neighbours. The population then evolves either by an individual giving birth to an offspring that takes over a random neighbour (birth-death process dynamics as the competition for resources already occupied by others) or by an individual constructing one new site from unexploited resources for its offspring (birth process dynamics as the competition for the unexploited resources which induces the extension of system). The underlying interaction network thus evolves and expands simultaneously with the population dynamics. The birth process dynamics is proved to be one new route that favours cooperators, under which cooperators can successfully resist the invasion of defectors in spite of large cost. Furthermore, under this “birth-death & birth” mechanism, the resulting network has a scale-free degree distribution, a small-world property, and hierarchical topology.

  1. EDITORIAL: Physics competitions Physics competitions

    NASA Astrophysics Data System (ADS)

    Jordens, H.; Mathelitsch, L.

    2010-07-01

    This editorial opens the second special section on physics competitions in European Journal of Physics. In the first section last year, we asked for feedback on the idea of such a section and on the content of the articles. We received no answer whatsoever, which can be interpreted in two ways: the section is not interesting enough to raise motivation for feedback, or the reader is satisfied. Having no indication which scenario is the correct one, we are optimistic and favour the second. The section at hand contains three articles. Again, as last year, the organizer of the annual Olympiad reports on tasks and outcomes of this competition. The Olympiad took place in Merida, Mexico, and was by far the largest event with 316 contestants from 68 countries. Again, the predominance of Asian/Chinese students was manifest, showing how serious the training is taken by both their authorities and students. Unfortunately, the winners of the last International Young Physicists' Tournament (IYPT), the team from Korea, did not accept the offer to report on their prize-winning contribution. We are thankful that two students from Austria, who achieved second place with their team, took over and reported on the task which they presented in the finals of the competition. It connects the fields of sport and physics and explains a special move in skateboarding. The third contribution introduces a different competition, 'International Conference of Young Scientists'. On one hand, as in the Olympiad, it addresses individuals, not teams. On the other, as in the IYPT, students have several months to prepare and also the quality of the presentation is an important element of the judgment. In fact, this competition comes closer to real scientific research compared to the other events. Finally and again, we hope that this section will serve several purposes: To show the competitions as a very important tool in the support of gifted students. To raise awareness amongst university teachers, and

  2. Sustainability and collapse in a coevolutionary model of local resource stocks and behavioral patterns on a social network

    NASA Astrophysics Data System (ADS)

    Wiedermann, Marc; Donges, Jonathan F.; Heitzig, Jobst; Kurths, Jürgen

    2014-05-01

    When investigating the causes and consequences of global change, the collective behavior of human beings is considered as having a considerable impact on natural systems. In our work, we propose a conceptual coevolutionary model simulating the dynamics of local renewable resources in interaction with simplistic societal agents exploiting those resources. The society is represented by a social network on which social traits may be transmitted between agents. These traits themselves induce a certain rate of exploitation of the resource, leading either to its depletion or sustainable existence. Traits are exchanged probabilistically according to their instantaneous individual payoff, and hence this process depends on the status of the natural resource. At the same time agents may adaptively restructure their set of acquaintances. Connections with agents having a different trait may be broken while new connections with agents of the same trait are established. We investigate which choices of social parameters, like the frequency of social interaction, rationality and rate of social network adaptation, cause the system to end in a sustainable state and, hence, what can be done to avoid a collapse of the entire system. The importance and influence of the social network structure is analyzed by the variation of link-densities in the underlying network topology and shows significant influence on the expected outcome of the model. For a static network with no adaptation we find a robust phase transition between the two different regimes, sustainable and non-sustainable, which co-exist in parameter space. High connectivity within the social network, e.g., high link-densities, in combination with a fast rate of social learning lead to a likely collapse of the entire co-evolutionary system, whereas slow learning and small network connectivity very likely result in the sustainable existence of the natural resources. Collapse may be avoided by an intelligent rewiring, e

  3. Social exclusion in finite populations

    NASA Astrophysics Data System (ADS)

    Li, Kun; Cong, Rui; Wu, Te; Wang, Long

    2015-04-01

    Social exclusion, keeping free riders from benefit sharing, plays an important role in sustaining cooperation in our world. Here we propose two different exclusion regimes, namely, peer exclusion and pool exclusion, to investigate the evolution of social exclusion in finite populations. In the peer exclusion regime, each excluder expels all the defectors independently, and thus bears the total cost on his own, while in the pool exclusion regime, excluders spontaneously form an institution to carry out rejection of the free riders, and each excluder shares the cost equally. In a public goods game containing only excluders and defectors, it is found that peer excluders outperform pool excluders if the exclusion costs are small, and the situation is converse once the exclusion costs exceed some critical points, which holds true for all the selection intensities and different update rules. Moreover, excluders can dominate the whole population under a suitable parameters range in the presence of second-order free riders (cooperators), showing that exclusion has prominent advantages over common costly punishment. More importantly, our finding indicates that the group exclusion mechanism helps the cooperative union to survive under unfavorable conditions. Our results may give some insights into better understanding the prevalence of such a strategy in the real world and its significance in sustaining cooperation.

  4. Exclusion processes with avalanches.

    PubMed

    Bhat, Uttam; Krapivsky, P L

    2014-07-01

    In an exclusion process with avalanches, when a particle hops to a neighboring empty site which is adjacent to an island the particle on the other end of the island immediately hops, and if it joins another island this triggers another hop. There are no restrictions on the length of the islands and the duration of the avalanche. This process is well defined in the low-density region ρ < 1/2. We describe the nature of steady states (on a ring) and determine all correlation functions. For the asymmetric version of the process, we compute the steady state current, and we describe shock and rarefaction waves which arise in the evolution of the step-function initial profile. For the symmetric version, we determine the diffusion coefficient and examine the evolution of a tagged particle.

  5. Frontier mutualism: coevolutionary patterns at the northern range limit of the leaf-cutter ant-fungus symbiosis.

    PubMed

    Mueller, Ulrich G; Mikheyev, Alexander S; Solomon, Scott E; Cooper, Michael

    2011-10-22

    Tropical leaf-cutter ants cultivate the fungus Attamyces bromatificus in a many-to-one, diffuse coevolutionary relationship where ant and fungal partners re-associate frequently over time. To evaluate whether ant-Attamyces coevolution is more specific (tighter) in peripheral populations, we characterized the host-specificities of Attamyces genotypes at their northern, subtropical range limits (southern USA, Mexico and Cuba). Population-genetic patterns of northern Attamyces reveal features that have so far not been observed in the diffusely coevolving, tropical ant-Attamyces associations. These unique features include (i) cases of one-to-one ant-Attamyces specialization that tighten coevolution at the northern frontier; (ii) distributions of genetically identical Attamyces clones over large areas (up to 81 000 km(2), approx. the area of Ireland, Austria or Panama); (iii) admixture rates between Attamyces lineages that appear lower in northern than in tropical populations; and (iv) long-distance gene flow of Attamyces across a dispersal barrier for leaf-cutter ants (ocean between mainland North America and Cuba). The latter suggests that Attamyces fungi may occasionally disperse independently of the ants, contrary to the traditional assumption that Attamyces fungi depend entirely on leaf-cutter queens for dispersal. Peripheral populations in Argentina or at mid-elevation sites in the Andes may reveal additional regional variants in ant-Attamyces coevolution. Studies of such populations are most likely to inform models of coextinctions of obligate mutualistic partners that are doubly stressed by habitat marginality and by environmental change.

  6. Target coverage optimisation of wireless sensor networks using a multi-objective immune co-evolutionary algorithm

    NASA Astrophysics Data System (ADS)

    Ding, Yong-Sheng; Lu, Xing-Jia; Hao, Kuang-Rong; Li, Long-Fei; Hu, Yi-Fan

    2011-09-01

    Target coverage is an important topic of wireless sensor networks. The target cover can be modelled as a minimal multi-objective vertex cover model with constraint of network connection. In order to search the optimal solution of the target cover set, we propose a multi-objective immune co-evolutionary algorithm (MOICEA) for target coverage. The MOICEA is inspired from the biological mechanisms of immune systems including clonal proliferation, hypermutation, co-evolution, immune elimination and memory mechanism. The affinity between antibody and antigen is used to measure the optimal target cover, and the affinity between antibodies is used to evaluate the diversity of population and to instruct the population evolution process. In order to examine the effectiveness of the MOICEA, we compare its performance with that of integer linear program and genetic algorithm in terms of four objectives while maintaining network connectivity. The experiment results show that the MOICEA can obtain promising performance in efficiently searching optimal vertex set by comparing with other approaches.

  7. Habitat area and structure affect the impact of seed predators and the potential for coevolutionary arms races.

    PubMed

    Mezquida, Eduardo T; Benkman, Craig W

    2010-03-01

    Both habitat patch size and structure affect the abundance and occurrence of species and thereby can affect the ecology and evolution of species interactions. Here we contrast the level of seed predation and selection exerted by Common Crossbills (Loxia curvirostra complex) and red squirrels (Sciurus vulgaris) in the extensive mountain pine (Pinus uncinata) forests in the Pyrenees with their level of seed predation in two small, isolated forests. Crossbills consumed 5.1 times more seeds in the Pyrenees than in the isolated forests, and six of seven cone traits under selection by crossbills were enhanced in the Pyrenees. In contrast, red squirrels tend to be uncommon in the open mountain pine forests, consuming relatively few seeds in both regions and having limited impact on both mountain pine and the interaction between crossbills and mountain pine. Resident crossbills in mountain pine forests in the Pyrenees have larger bills than in nearby forests, consistent with local adaptation by crossbills and a coevolutionary arms race between crossbills and mountain pine. The mechanisms leading to variation in the interaction between crossbills and mountain pine should be general to many systems because habitat patch size and structure often vary across the range of a species.

  8. Community-level competition: asymmetrical dominance.

    PubMed Central

    Gilpin, M

    1994-01-01

    Ecological competition between entire communities of species occurs only when geographic barriers are suddenly removed. Recent empirical analysis suggests that, following the disappearance of a barrier, one community may swamp a second community, causing most or all of its species to go extinct. I provide theoretical insight into this result by showing that two "naive" competition communities mix randomly following the removal of a barrier. However, if the two communities have been "assembled," or self-organized, through a history of competitive exclusion, the communities are likely to battle as coordinated armies, with one or the other side ultimately claiming the entire landscape. PMID:8159734

  9. EDITORIAL: Physics competitions Physics competitions

    NASA Astrophysics Data System (ADS)

    Jordens, H.; Mathelitsch, L.

    2011-07-01

    International tests on competences, such as TIMSS or PISA, and knowledge of young students have revealed low average scores in many countries, often unexpectedly. One effective measure to increase the average standard of a population is to bring the last third of the group to a higher level. Therefore, many nations put some effort into this activity. This brings the danger that not enough attention is paid to students at the other end, those who are talented. Indeed, it is a very difficult task for a teacher to support the less able and at the same time challenge the gifted students, to lead them to the limits of their abilities and provide for a smooth transition to university study. Physics competitions have been proven to fulfil these last demands to a large degree, and therefore are an important additional and, to some extent, complementary tool for the promotion of talented students. This third special section on physics competitions in European Journal of Physics contains three papers, each dealing with a different form of science contest. The first continues the series of presentations of tasks performed at the International Young Physicists' Tournament, which was held in Vienna in 2011. First place went to the team from Singapore, and they have put their investigation on vertical oscillations of coupled magnets into written form (not required by the tournament, where an oral presentation and a defence and discussion are the central aspects). Their paper shows how rich in physics this problem is, and what level of solutions high-school students can already achieve. Sadly, those responsible for the organization of last year's International Physics Olympiad did not provide us with a report on this competition. This is unfortunate, since the Olympiad in Zagreb was very successful and, in particular, the experimental tasks were creative and demanding. Very similar to the aims and the execution of the Physics Olympiad is the International Olympiad on Astronomy

  10. Exclusion performance and learning by exclusion in dogs.

    PubMed

    Zaine, Isabela; Domeniconi, Camila; de Rose, Julio C

    2016-05-01

    Responding by exclusion is a type of emergent repertoire in which an individual chooses an alternative by the apparent exclusion of other available alternatives. In this case it is possible to respond appropriately to an undefined stimulus (one that has not previously acquired discriminative functions) by excluding the defined alternatives. There is evidence of exclusion in humans and nonhuman animals, although learning as an outcome of exclusion does not always occur. This study aimed to investigate exclusion in visual simple discriminations and learning of new simple discriminations resulting from exclusion in four border collies. Subjects were trained to perform simple simultaneous discriminations between pairs of tridimensional objects, and were then tested for exclusion, novelty control and learning of new simple discriminations. All dogs successfully responded by exclusion, choosing an undefined stimulus displayed with an S-. For three dogs, it was possible to conclude that these previously undefined stimuli acquired S+ functions, documenting learning of new simple discriminations. However, this required up to four exposures to exclusion trials with each pair of stimuli.

  11. Competition and coexistence with multiple life-history stages.

    PubMed

    Moll, Jason D; Brown, Joel S

    2008-06-01

    Do complex life histories affect the conditions under which competitors can coexist? We investigated this using a two-species, two-stage Ricker model. With complex life cycles, the competition coefficients associated with each life-history stage suggest one of three competitive outcomes-coexistence, alternate stable states, or competitive exclusion-that depend on the relative magnitudes of intraspecific and interspecific competition. When the two stages suggest the same outcome, only that outcome can occur. When the stages suggest different outcomes, either one may prevail. It is also possible to have emergent outcomes, in which the outcome is not suggested by either stage. This can occur when the two stages suggest competitive exclusion by opposite species or when one stage suggests alternate stable states and the other suggests coexistence. Therefore, determining the mechanisms of coexistence in species with complex life histories may require consideration of competitive interactions within all life-history stages.

  12. Exclusive Processes in Quantum Chromodynamics

    NASA Astrophysics Data System (ADS)

    Brodsky, Stanley J.; Peter Lepage, G.

    The following sections are included: * INTRODUCTION * NONRELATIVISTIC FORM FACTORS FOR HEAVY-QUARK MESONS * HADRONIC WAVEFUNCTIONS * DEFINITIONS * LIGHT-CONE BOUND-STATE EQUATIONS * GENERAL PROPERTIES OF LIGHT-CONE WAVEFUNCTIONS * RENORMALIZATION * CALCULATING * A PERTURBATIVE ANALYSIS * FACTORIZATION—LEADING ORDER ANALYSIS * THE QUARK DISTRIBUTION AMPLITUDE * DETERMINATION OF DISTRIBUTION AMPLITUDES * HIGHER ORDER ANALYSIS * COMPLICATIONS * How LARGE IS ASYMPTOTIC Q? * APPLICATIONS OF QCD TO THE PHENOMENOLOGY OF EXCLUSIVE REACTIONS * GENERAL FEATURES OF EXCLUSIVE PROCESSES IN QCD * ELECTROMAGNETIC FORM FACTORS * COMPARISON OF QCD SCALING WITH EXPERIMENT * EXCLUSIVE ANTI-PROTON PROTON ANNIHILATION PROCESSES * ADDITIONAL TESTS OF GLUON SPIN IN EXCLUSIVE PROCESSES * HADRONIC WAVEFUNCTION PHENOMENOLOGY * CALCULATING TH * THE PRE-QCD DEVELOPMENT OF EXCLUSIVE REACTIONS * EXCLUSIVE e+ e- ANNIHILATION PROCESSES * J/ψ DECAY TO HADRON PAIRS * THE π-ρ PUZZLE * FORM FACTOR ZEROS IN QCD * EXCLUSIVE γγ REACTIONS * QCD PROCESSES IN NUCLEI * EXCLUSIVE NUCLEAR REACTIONS - REDUCED AMPLITUDES * COLOR TRANSPARENCY * SPIN CORRELATIONS IN PROTON-PROTON SCATTERING * CONCLUSIONS * APPENDIX I BARYON FORM FACTORS AND EVOLUTION EQUATIONS * APPENDIX II LIGHT CONE QUANTIZATION AND PERTURBATION THEORY * APPENDIX III A NONPERTURBATIVE ANALYSIS OF EXCLUSIVE REACTIONS-DISCRETIZED LIGHT-CONE QUANTIZATION * ACKNOWLEDGEMENTS * REFERENCES

  13. Competition promotes the persistence of populations in ecosystems

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Duan, Jinqiao; Liu, Tong

    2016-07-01

    Competition is one of the most common form in ecological systems, which plays important roles in population dynamics. However, the influences of competition on persistence of populations remain unclear when space effect is included. In this paper, we investigated a predator-prey model with competition and spatial diffusion. Based on pattern formations and time series of populations, we found that competitions induce the persistence of populations, which denies competitive exclusion principle. Moreover, we testify the robustness of these effects. Our results also suggest that space may lead to the emergence of new phenomenon in ecosystems.

  14. Competition promotes the persistence of populations in ecosystems

    PubMed Central

    Wang, Tao; Duan, Jinqiao; Liu, Tong

    2016-01-01

    Competition is one of the most common form in ecological systems, which plays important roles in population dynamics. However, the influences of competition on persistence of populations remain unclear when space effect is included. In this paper, we investigated a predator-prey model with competition and spatial diffusion. Based on pattern formations and time series of populations, we found that competitions induce the persistence of populations, which denies competitive exclusion principle. Moreover, we testify the robustness of these effects. Our results also suggest that space may lead to the emergence of new phenomenon in ecosystems. PMID:27460143

  15. Amino acid positions subject to multiple co-evolutionary constraints can be robustly identified by their eigenvector network centrality scores

    PubMed Central

    Parente, Daniel J.; Ray, J. Christian J.; Swint-Kruse, Liskin

    2015-01-01

    As proteins evolve, amino acid positions key to protein structure or function are subject to mutational constraints. These positions can be detected by analyzing sequence families for amino acid conservation or for co-evolution between pairs of positions. Co-evolutionary scores are usually rank-ordered and thresholded to reveal the top pairwise scores, but they also can be treated as weighted networks. Here, we used network analyses to bypass a major complication of co-evolution studies: For a given sequence alignment, alternative algorithms usually identify different, top pairwise scores. We reconciled results from five commonly-used, mathematically divergent algorithms (ELSC, McBASC, OMES, SCA, and ZNMI), using the LacI/GalR and 1,6-bisphosphate aldolase protein families as models. Calculations used unthresholded co-evolution scores from which column-specific properties such as sequence entropy and random noise were subtracted; “central” positions were identified by calculating various network centrality scores. When compared among algorithms, network centrality methods, particularly eigenvector centrality, showed markedly better agreement than comparisons of the top pairwise scores. Positions with large centrality scores occurred at key structural locations and/or were functionally sensitive to mutations. Further, the top central positions often differed from those with top pairwise co-evolution scores: Instead of a few strong scores, central positions often had multiple, moderate scores. We conclude that eigenvector centrality calculations reveal a robust evolutionary pattern of constraints – detectable by divergent algorithms – that occur at key protein locations. Finally, we discuss the fact that multiple patterns co-exist in evolutionary data that, together, give rise to emergent protein functions. PMID:26503808

  16. Frontier mutualism: coevolutionary patterns at the northern range limit of the leaf-cutter ant–fungus symbiosis

    PubMed Central

    Mueller, Ulrich G.; Mikheyev, Alexander S.; Solomon, Scott E.; Cooper, Michael

    2011-01-01

    Tropical leaf-cutter ants cultivate the fungus Attamyces bromatificus in a many-to-one, diffuse coevolutionary relationship where ant and fungal partners re-associate frequently over time. To evaluate whether ant–Attamyces coevolution is more specific (tighter) in peripheral populations, we characterized the host-specificities of Attamyces genotypes at their northern, subtropical range limits (southern USA, Mexico and Cuba). Population-genetic patterns of northern Attamyces reveal features that have so far not been observed in the diffusely coevolving, tropical ant–Attamyces associations. These unique features include (i) cases of one-to-one ant–Attamyces specialization that tighten coevolution at the northern frontier; (ii) distributions of genetically identical Attamyces clones over large areas (up to 81 000 km2, approx. the area of Ireland, Austria or Panama); (iii) admixture rates between Attamyces lineages that appear lower in northern than in tropical populations; and (iv) long-distance gene flow of Attamyces across a dispersal barrier for leaf-cutter ants (ocean between mainland North America and Cuba). The latter suggests that Attamyces fungi may occasionally disperse independently of the ants, contrary to the traditional assumption that Attamyces fungi depend entirely on leaf-cutter queens for dispersal. Peripheral populations in Argentina or at mid-elevation sites in the Andes may reveal additional regional variants in ant–Attamyces coevolution. Studies of such populations are most likely to inform models of coextinctions of obligate mutualistic partners that are doubly stressed by habitat marginality and by environmental change. PMID:21389026

  17. Exclusive meson production at HERMES

    NASA Astrophysics Data System (ADS)

    Vandenbroucke, A.

    2005-10-01

    Generalized Parton Distributions (GPDs) provide a new level of insight into the quark structure of the nucleon. Experimentally they can be probed by hard exclusive electroproduction of both scalar and vector mesons. Results for the cross section for the reaction ep → enπ+, and a first result for the asymmetry AUT for exclusive ρ0 production are presented.

  18. Evaluating Alternatives to Exclusive "He."

    ERIC Educational Resources Information Center

    Todd-Mancillas, William R.

    A study was conducted to determine the effects on reading comprehension of the use of the exclusive pronoun "he" and more or less contrived alternatives. Subjects, 358 students enrolled in an introduction to human communication at a large northeastern university, read three different forms of the same essay. One essay form exclusively used "he,"…

  19. Competitive Science: Is Competition Ruining Science?

    PubMed Central

    Casadevall, Arturo

    2015-01-01

    Science has always been a competitive undertaking. Despite recognition of the benefits of cooperation and team science, reduced availability of funding and jobs has made science more competitive than ever. Here we consider the benefits of competition in providing incentives to scientists and the adverse effects of competition on resource sharing, research integrity, and creativity. The history of science shows that transformative discoveries often occur in the absence of competition, which only emerges once fields are established and goals are defined. Measures to encourage collaboration and ameliorate competition in the scientific enterprise are discussed. PMID:25605760

  20. Lunabotics Mining Competition

    NASA Technical Reports Server (NTRS)

    Mueller, Rob; Murphy, Gloria

    2010-01-01

    This slide presentation describes a competition to design a lunar robot (lunabot) that can be controlled either remotely or autonomously, isolated from the operator, and is designed to mine a lunar aggregate simulant. The competition is part of a systems engineering curriculum. The 2010 competition winners in five areas of the competition were acknowledged, and the 2011 competition was announced.

  1. Competitive spirit

    NASA Astrophysics Data System (ADS)

    2000-01-01

    Leicester University will host the 65 international teams of students who will assemble in July for this year's International Physics Olympiad . The last time the Olympiad came to the UK was in 1986 in London, and it was the notable enthusiasm of the Leicester Physics and Astronomy department which persuaded the Olympiad Committee to give them the chance of organizing the prestigious event. The students taking part from all over the world are studying physics at A-level or an equivalent standard and they will take part in an intellectual marathon of theoretical and practical examinations. Each national team comprises five students selected from three rounds of competition and the teams will receive an official welcome from the city, as well as opportunities to visit some of the important educational and cultural centres of the surrounding region. The finalists will also be able to test their skills and initiative at the Challenger Learning Centre, which forms part of Leicester's new National Space Science Centre. Specific information on the event can be found on the Olympiad-2000 website at www.star.le.ac.uk/IphO-2000 . The Rudolf Ortvay problem solving contest in physics, which takes place in November, is a tradition of Eötvös University in Budapest, Hungary. The competition was first opened to international participants in 1998, enabling students from universities around the world to show their knowledge, ingenuity, problem-solving skills and physical insight into problems that are far beyond routine level. The problems (30 - 35 each year) are chosen from different branches of theoretical as well as applied physics. They have varying levels of difficulty, and every contestant can send solutions for ten problems. The focus is not on school-level problem-solving routines but rather on the `physical' way of thinking, recognition of the heart of the problem and an appropriate choice of mathematics. The majority of the assigned problems are original, few having

  2. Computational Analysis of Residue Interaction Networks and Coevolutionary Relationships in the Hsp70 Chaperones: A Community-Hopping Model of Allosteric Regulation and Communication

    PubMed Central

    Stetz, Gabrielle; Verkhivker, Gennady M.

    2017-01-01

    Allosteric interactions in the Hsp70 proteins are linked with their regulatory mechanisms and cellular functions. Despite significant progress in structural and functional characterization of the Hsp70 proteins fundamental questions concerning modularity of the allosteric interaction networks and hierarchy of signaling pathways in the Hsp70 chaperones remained largely unexplored and poorly understood. In this work, we proposed an integrated computational strategy that combined atomistic and coarse-grained simulations with coevolutionary analysis and network modeling of the residue interactions. A novel aspect of this work is the incorporation of dynamic residue correlations and coevolutionary residue dependencies in the construction of allosteric interaction networks and signaling pathways. We found that functional sites involved in allosteric regulation of Hsp70 may be characterized by structural stability, proximity to global hinge centers and local structural environment that is enriched by highly coevolving flexible residues. These specific characteristics may be necessary for regulation of allosteric structural transitions and could distinguish regulatory sites from nonfunctional conserved residues. The observed confluence of dynamics correlations and coevolutionary residue couplings with global networking features may determine modular organization of allosteric interactions and dictate localization of key mediating sites. Community analysis of the residue interaction networks revealed that concerted rearrangements of local interacting modules at the inter-domain interface may be responsible for global structural changes and a population shift in the DnaK chaperone. The inter-domain communities in the Hsp70 structures harbor the majority of regulatory residues involved in allosteric signaling, suggesting that these sites could be integral to the network organization and coordination of structural changes. Using a network-based formalism of allostery, we

  3. Selection on female remating interval is influenced by male sperm competition strategies and ejaculate characteristics

    PubMed Central

    Alonzo, Suzanne H.; Pizzari, Tommaso

    2013-01-01

    Female remating rate dictates the level of sperm competition in a population, and extensive research has focused on how sperm competition generates selection on male ejaculate allocation. Yet the way ejaculate allocation strategies in turn generate selection on female remating rates, which ultimately influence levels of sperm competition, has received much less consideration despite increasing evidence that both mating itself and ejaculate traits affect multiple components of female fitness. Here, we develop theory to examine how the effects of mating on female fertility, fecundity and mortality interact to generate selection on female remating rate. When males produce more fertile ejaculates, females are selected to mate less frequently, thus decreasing levels of sperm competition. This could in turn favour decreased male ejaculate allocation, which could subsequently lead to higher female remating. When remating simultaneously increases female fecundity and mortality, females are selected to mate more frequently, thus exacerbating sperm competition and favouring male traits that convey a competitive advantage even when harmful to female survival. While intuitive when considered separately, these predictions demonstrate the potential for complex coevolutionary dynamics between male ejaculate expenditure and female remating rate, and the correlated evolution of multiple male and female reproductive traits affecting mating, fertility and fecundity. PMID:23339235

  4. 47 CFR 80.1251 - Maritime communications subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Maritime communications subject to competitive... AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Competitive Bidding Procedures § 80.1251 Maritime communications subject to competitive bidding. Mutually exclusive initial applications for VPCSA...

  5. Competition and Cheating

    MedlinePlus

    ... of competition. In our culture, with few exceptions, competitiveness is commonplace and in fact is rewarded. Children ... or card games, and you will recognize the competitiveness, striving and social learning taking place and sometimes ...

  6. Evolution of angiosperm seed disperser mutualisms: the timing of origins and their consequences for coevolutionary interactions between angiosperms and frugivores.

    PubMed

    Eriksson, Ove

    2016-02-01

    , and many of the originations of fleshy fruits occurred well after the peak in the early Eocene. (vi) During periods associated with environmental change altering coevolutionary networks and opening of niche space, reciprocal coevolution may result in strong directional selection formative for both fruit and frugivore evolution. Further evidence is needed to test this hypothesis. Based on the abundance of plant lineages with various forms of fleshy fruits, and the diversity of frugivores, it is suggested that periods of rapid coevolution in angiosperms and frugivores occurred numerous times during the 80 million years of angiosperm-frugivore evolution.

  7. 78 FR 55687 - Notice of Intent To Grant an Exclusive, Partially Exclusive or Non-Exclusive License of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... prospective exclusive, partially exclusive, or non-exclusive license of the following U.S. Patent Application... business at 201 Ruther Drive, Suite 3, Newark, DE 19711. DATES: Written objections must be filed not later...

  8. Coevolution between invasive and native plants driven by chemical competition and soil biota.

    PubMed

    Lankau, Richard A

    2012-07-10

    Although reciprocal evolutionary responses between interacting species are a driving force behind the diversity of life, pairwise coevolution between plant competitors has received less attention than other species interactions and has been considered relatively less important in explaining ecological patterns. However, the success of species transported across biogeographic boundaries suggests a stronger role for evolutionary relationships in shaping plant interactions. Alliaria petiolata is a Eurasian species that has invaded North American forest understories, where it competes with native understory species in part by producing compounds that directly and indirectly slow the growth of competing species. Here I show that populations of A. petiolata from areas with a greater density of interspecific competitors invest more in a toxic allelochemical under common conditions. Furthermore, populations of a native competitor from areas with highly toxic invaders are more tolerant to competition from the invader, suggesting coevolutionary dynamics between the species. Field reciprocal transplants confirmed that native populations more tolerant to the invader had higher fitness when the invader was common, but these traits came at a cost when the invader was rare. Exotic species are often detrimentally dominant in their new range due to their evolutionary novelty; however, the development of new coevolutionary relationships may act to integrate exotic species into native communities.

  9. Female competition: causes, constraints, content, and contexts.

    PubMed

    Campbell, Anne

    2004-02-01

    Monogamy tends to equalise mate competition between the sexes. However, women show greater restraint in their use of direct intrasexual aggression, which, I argue, is a result of their higher parental investment and the consequently greater reproductive cost of injury or death. Women usually compete for mates by advertising qualities valued by men (beauty and sexual exclusiveness) and by using indirect means of denigrating rivals (through gossip and stigmatisation). However, where well-resourced men are in short supply, women must find alternative sources of support or escalate their competition for male partners to physical levels. Data from criminology, psychology, evolutionary biology, and anthropology are used to support these proposals.

  10. Coevolutionary Free Lunches

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.; Macready, William G.

    2005-01-01

    Recent work on the mathematical foundations of optimization has begun to uncover its rich structure. In particular, the "No Free Lunch" (NFL) theorems state that any two algorithms are equivalent when their performance is averaged across all possible problems. This highlights the need for exploiting problem-specific knowledge to achieve better than random performance. In this paper we present a general framework covering more search scenarios. In addition to the optimization scenarios addressed in the NFL results, this framework covers multi-armed bandit problems and evolution of multiple co-evolving players. As a particular instance of the latter, it covers "self-play" problems. In these problems the set of players work together to produce a champion, who then engages one or more antagonists in a subsequent multi-player game. In contrast to the traditional optimization case where the NFL results hold, we show that in self-play there are free lunches: in coevolution some algorithms have better performance than other algorithms, averaged across all possible problems. We consider the implications of these results to biology where there is no champion.

  11. Classification as clustering: a Pareto cooperative-competitive GP approach.

    PubMed

    McIntyre, Andrew R; Heywood, Malcolm I

    2011-01-01

    Intuitively population based algorithms such as genetic programming provide a natural environment for supporting solutions that learn to decompose the overall task between multiple individuals, or a team. This work presents a framework for evolving teams without recourse to prespecifying the number of cooperating individuals. To do so, each individual evolves a mapping to a distribution of outcomes that, following clustering, establishes the parameterization of a (Gaussian) local membership function. This gives individuals the opportunity to represent subsets of tasks, where the overall task is that of classification under the supervised learning domain. Thus, rather than each team member representing an entire class, individuals are free to identify unique subsets of the overall classification task. The framework is supported by techniques from evolutionary multiobjective optimization (EMO) and Pareto competitive coevolution. EMO establishes the basis for encouraging individuals to provide accurate yet nonoverlaping behaviors; whereas competitive coevolution provides the mechanism for scaling to potentially large unbalanced datasets. Benchmarking is performed against recent examples of nonlinear SVM classifiers over 12 UCI datasets with between 150 and 200,000 training instances. Solutions from the proposed coevolutionary multiobjective GP framework appear to provide a good balance between classification performance and model complexity, especially as the dataset instance count increases.

  12. Competition in Education.

    ERIC Educational Resources Information Center

    Rich, John Martin; DeVitis, Joseph L.

    This book discusses various major aspects of competition in education. It identifies competition within educational policies, programs, and practices, as well as the problems that certain forms of competition create. It also traces the influences of American competitive values on education. Chapter 1 provides an introductory overview of the…

  13. Competition in Education.

    ERIC Educational Resources Information Center

    Rich, John Martin; DeVitis, Joseph L.

    This book discusses various major aspects of competition in education. It identifies competition within educational policies, programs, and practices, as well as the problems that certain forms of competition create. It also traces the influences of American competitive values on education. Chapter 1 provides an introductory overview of the…

  14. Competition in the Marketplace.

    ERIC Educational Resources Information Center

    Schug, Mark C.; And Others

    1984-01-01

    The conceptual introduction to this issue focuses on two questions: why study competition and what is a competitive market. Four instructional units follow, beginning with "Choosing Competitors." This preschool and kindergarten unit involves students in competitive games (naming colors), role playing competitive behaviors, comparing…

  15. Competitive sourcing: From captivity to competition

    SciTech Connect

    1994-12-31

    Eleven papers were presented at Elcon`s Annual Seminar on Electric Issues held on October 13-14, 1994 in Washington, DC. The theme of the conference was on competitive sourcing: From Captivity to Competition. The following topics were discussed: the FERC and competition in the electric power markets; the industrial role in the changing electric industry; commercials and residentials; the development of electricity futures; earthquakes in the states: Michigan experience; the loss of industrial load; competitive sourcing; municipalization; power marketing; and what is a non-sham wholesaler. A separate abstract was prepared for each paper for inclusion in the Energy Science and Technology Database.

  16. The relative importance of seed competition, resource competition and perturbations on community structure

    NASA Astrophysics Data System (ADS)

    Bohn, K.; Dyke, J. G.; Pavlick, R.; Reineking, B.; Reu, B.; Kleidon, A.

    2011-05-01

    While the regional climate is the primary selection pressure for whether a plant strategy can survive, however, competitive interactions strongly affect the relative abundances of plant strategies within communities. Here, we investigate the relative importance of competition and perturbations on the development of vegetation community structure. To do so, we develop DIVE (Dynamics and Interactions of VEgetation), a simple general model that links plant strategies to their competitive dynamics, using growth and reproduction characteristics that emerge from climatic constraints. The model calculates population dynamics based on establishment, mortality, invasion and exclusion in the presence of different strengths of perturbations, seed and resource competition. The highest levels of diversity were found in simulations without competition as long as mortality is not too high. However, reasonable successional dynamics were only achieved when resource competition is considered. Under high levels of competition, intermediate levels of perturbations were required to obtain coexistence. Since succession and coexistence are observed in plant communities, we conclude that the DIVE model with competition and intermediate levels of perturbation represents an adequate way to model population dynamics. Because of the simplicity and generality of DIVE, it could be used to understand vegetation structure and functioning at the global scale and the response of vegetation to global change.

  17. Physics Competitions in Hungary

    NASA Astrophysics Data System (ADS)

    Lugosi, ErzséBet SzéP, Jenö

    The following sections are included: * Description of Physics Competitions in Hungary * Training of the Hungarian Team before the International Physics Olympiad * Few Problems for the Hungarian National Physics Competition for 15 - 16 Year Old students * Problems for the Hungarian National Physics Competition in 1989 for 17 - 18 Year Old Students * Experimental Problems for the Competition of KöMAL for 15 - 18 Year Old Students * Problems for the Hungarian National Physics Competition in 1989 for 17 - 18 Year Old Students * solving this equation we obtain m = 18kg * The work done is 427 joule - 80 joule 347 joule * Experimental Problems for the Competition of KöMAL for 15 - 18 Pear Old Students

  18. Overcoming Exclusion through Adult Learning.

    ERIC Educational Resources Information Center

    Nash, Ian; Walshe, John

    Strategies for overcoming exclusion through adult learning were identified through case studies of 19 initiatives in the following countries: Belgium; Mexico; the Netherlands; Norway; Portugal; and the United Kingdom. The study programs involved a diverse array of formal, nonformal, and informal public sector, community, and enterprise-based…

  19. University Ranking as Social Exclusion

    ERIC Educational Resources Information Center

    Amsler, Sarah S.; Bolsmann, Chris

    2012-01-01

    In this article we explore the dual role of global university rankings in the creation of a new, knowledge-identified, transnational capitalist class and in facilitating new forms of social exclusion. We examine how and why the practice of ranking universities has become widely defined by national and international organisations as an important…

  20. Exclusive processes in quantum chromodynamics

    SciTech Connect

    Brodsky, S.J.; Lepage, G.P.

    1981-06-01

    Large momentum transfer exclusive processes and the short distance structure of hadronic wave functions can be systematically analyzed within the context of perturbative QCD. Predictions for meson form factors, two-photon processes ..gamma gamma.. ..-->.. M anti M, hadronic decays of heavy quark systems, and a number of other related QCD phenomena are reviewed.

  1. University Ranking as Social Exclusion

    ERIC Educational Resources Information Center

    Amsler, Sarah S.; Bolsmann, Chris

    2012-01-01

    In this article we explore the dual role of global university rankings in the creation of a new, knowledge-identified, transnational capitalist class and in facilitating new forms of social exclusion. We examine how and why the practice of ranking universities has become widely defined by national and international organisations as an important…

  2. Lunar Regolith Excavation Competition

    NASA Technical Reports Server (NTRS)

    Liles, Cassandra

    2009-01-01

    The Lunar Regolith Excavation Competition is a new competition that needs graphics, logos, rules, as well as an arena. Although this is the first year of the competition, the competition is modeled after an existing competition, the Centennial Lunar Excavator Challenge. This competition however is aimed at college students. This makes the challenge identifying key aspects of the original competition and modeling them to fit into an easier task, and creating exciting advertisement that helps encourage participation. By using a youth focus group, young insight, as well as guiding advice from experts in the field, hopefully an arena can be designed and built, rules can be molded and created to fit, and alluring graphics can be printed to bring about a successful first year of the Lunar Regolith Excavation Competition.

  3. Diversifying evolution of competitiveness.

    PubMed

    Baldauf, Sebastian A; Engqvist, Leif; Weissing, Franz J

    2014-10-29

    In many species, individuals express phenotypic characteristics that enhance their competitiveness, that is, the ability to acquire resources in competition with others. Moreover, the degree of competitiveness varies considerably across individuals and in time. By means of an evolutionary model, we provide an explanation for this finding. We make the assumption that investment into competitiveness enhances the probability to acquire a high-quality resource, but at the same time reduces the ability of exploiting acquired resources with maximal efficiency. The model reveals that under a broad range of conditions competitiveness either converges to a polymorphic state, where individuals differing in competitive ability stably coexist, or is subject to perpetual transitions between periods of high and low competitiveness. The dynamics becomes even more complex if females can evolve preferences for (or against) competitive males. In extreme cases, such preferences can even drive the population to extinction.

  4. Competition for Assistance Agreements

    EPA Pesticide Factsheets

    It is EPA policy to promote competition in the award of assistance agreements to the maximum extent practicable.When assistance agreements are awarded competitively, it is EPA policy that the competitive process be fair and open & that no applicant receive

  5. Strategizing for Intense Competition.

    ERIC Educational Resources Information Center

    Hahn, William; Bourgeois, Ernest J., Jr.

    1999-01-01

    Examines trend toward more aggressive student recruiting strategies by colleges and universities, applying a model that assesses five competitive forces-cause and effect of competition, the expanding marketplace, substitute products, buyer power, and supplier power, and examines various strategies for dealing with these competitive forces, such as…

  6. In Defence of Competition.

    ERIC Educational Resources Information Center

    Prvulovich, Zika Rad

    1982-01-01

    Examines objections to competition as presented by educational philosopher Michael Fielding and others. The two major types of criticism of competition are that it is unfair and divisive and that it is selfish and immoral. The author advocates educational experiences which combine self-competition with cooperation. (AM)

  7. Competition and Intrinsic Motivation.

    ERIC Educational Resources Information Center

    Tripathi, Kailas Nath

    1992-01-01

    Reports on a study of competition, motivation, and performance among 60 adolescents in India. Finds that direct competition with another person led to higher levels of immediate performance. Also finds that indirect competition against a pre-set standard resulted in greater intrinsic motivation. (CFR)

  8. Research on Competitions.

    ERIC Educational Resources Information Center

    Burnsed, Vernon; Sochinski, James

    1983-01-01

    Marching band competition has become a major factor in instrumental music education. Studies reveal that directors, administrators, parents and students see the benefits of marching contests as mainly extra-musical. High school students and college freshmen had the most positive attitudes toward marching competition. The impact of competition on…

  9. In Defence of Competition.

    ERIC Educational Resources Information Center

    Prvulovich, Zika Rad

    1982-01-01

    Examines objections to competition as presented by educational philosopher Michael Fielding and others. The two major types of criticism of competition are that it is unfair and divisive and that it is selfish and immoral. The author advocates educational experiences which combine self-competition with cooperation. (AM)

  10. Strategizing for Intense Competition.

    ERIC Educational Resources Information Center

    Hahn, William; Bourgeois, Ernest J., Jr.

    1999-01-01

    Examines trend toward more aggressive student recruiting strategies by colleges and universities, applying a model that assesses five competitive forces-cause and effect of competition, the expanding marketplace, substitute products, buyer power, and supplier power, and examines various strategies for dealing with these competitive forces, such as…

  11. Competition in benthic marine invertebrates: the unrecognized role of exploitative competition for oxygen.

    PubMed

    Ferguson, Nick; White, Craig R; Marshall, Dustin J

    2013-01-01

    Competition is a ubiquitous structuring force across systems, but different fields emphasize the role of different types of competition. In benthic marine environments, where some of the classic examples of competition were described, there is a strong emphasis on interference competition: marine invertebrates are assumed to compete fiercely for the limiting resource of space. Much of our understanding of the dynamics of this system is based on this assumption, yet empirical studies often find that increases in density can reduce performance despite free space being available. Furthermore, the assumption that space is the exclusively limiting resource raises paradoxes regarding species coexistence in this system. Here, we measure the availability of oxygen in the field and in the laboratory, as well as the tolerance of resident species to low-oxygen conditions. We show that oxygen can be the primary limiting resource in some instances, and that exploitative competition for this resource is very likely among benthic marine invertebrates. Furthermore, growth form (and the associated risk of oxygen limitation) covaries with the ability to withstand oxygen-poor conditions across a wide range of taxa. Oxygen availability at very small scales may influence the distribution and abundance of sessile marine invertebrates more than is currently appreciated. Furthermore, competition for multiple resources (space and oxygen) and trade-offs in competitive ability for each may promote coexistence in this system.

  12. Intrapersonal and interpersonal processes of social exclusion

    PubMed Central

    Kawamoto, Taishi; Ura, Mitsuhiro; Nittono, Hiroshi

    2015-01-01

    People have a fundamental need to belong with others. Social exclusion impairs this need and has various effects on cognition, affect, and the behavior of excluded individuals. We have previously reported that activity in the dorsal anterior cingulate cortex (dACC) and right ventrolateral prefrontal cortex (rVLPFC) could be a neurocognitive index of social exclusion (Kawamoto et al., 2012). In this article, we provide an integrative framework for understanding occurrences during and after social exclusion, by reviewing neuroimaging, electrophysiological, and behavioral studies of dACC and rVLPFC, within the framework of intrapersonal and interpersonal processes of social exclusion. As a result, we have indicated directions for future studies to further clarify the phenomenon of social exclusion from the following perspectives: (1) constructional elements of social exclusion, (2) detection sensitivity and interpretation bias in social exclusion, (3) development of new methods to assess the reactivity to social exclusion, and (4) sources of social exclusion. PMID:25798081

  13. Nanofluidic Size-Exclusion Chromatograph

    NASA Technical Reports Server (NTRS)

    Feldman, Sabrina; Svehla, Danielle; Grunthaner, Frank; Feldman, Jason; Shakkottai, P.

    2004-01-01

    Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a laboratory on a chip that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically, it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples. Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size-exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of molecules: basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights. Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights.

  14. Exclusive breastfeeding: measurement and indicators.

    PubMed

    Greiner, Ted

    2014-01-01

    Accurate measurement of the duration of exclusive breastfeeding is complicated by factors related to definitions, timing, duration of recall, methods of analysis, and sample biases. Clearly prospective methods are likely to be more accurate but are too expensive to use in most large-scale surveys. Internationally, most surveys use a point-in-time or current status measurement (usually 24-hour recall) and report their findings using an indicator established by the World Health Organisation (WHO) in 1991 that involves combining all babies less than six months old in order to obtain a large enough sample size to result in stable proportions that can be compared over time. However, this indicator is complex to understand and explain and is widely misunderstood, even within the breastfeeding community. It is commonly cited in ways that greatly exaggerate how common exclusive breastfeeding actually is. A life-long or since birth indicator, introduced in 2000, counts infants as no longer exclusively breastfed as soon as anything else is fed to them. This is appropriate to do if for example data are being used to link infant feeding patterns with vertical transmission of HIV or later patterns of infant allergy. However, this indicator underestimates the total extent of exclusive breastfeeding, since some women interrupt but then resume it after a period of supplementation (which could for example only be a small amount of water given a single time). Exactly which indicator is best to use depends on the purpose for which the data are being used. However, for surveys, the best approach, rarely used, would be to report indicators based on both point-in-time and life-long data.

  15. Supplementing managed competition.

    PubMed

    Higgins, W

    President Clinton's proposal for health care reform calls for managed competition within global expenditure targets. However, it is unlikely that health plans will have sufficient leverage with providers to negotiate arrangements consistent with expenditure targets in nonurban areas. This paper describes a reimbursement system based on competitive prospective payment and capitation (CPPC) which can supplement managed competition in less populous areas or replace managed competition should that strategy prove unsuccessful. The CPPC system is capable of enforcing an expenditure target while encouraging the formation of capitated networks and creating strong incentives for efficiency. It is generally compatible with the Clinton administration's version of managed competition.

  16. Competition among hospitals.

    PubMed

    Noether, M

    1988-09-01

    The traditional view of hospital competition has posited that hospitals compete primarily along 'quality' dimensions, in the form of fancy equipment to attract admitting physicians and pleasant surroundings to entice patients. Price competition among hospitals is thought to be non-existent. This paper estimates the effects of various hospital market characteristics on hospital prices and expenses in an attempt to determine the form of hospital competition. The results suggest that both price and quality competition are greater in markets that are less concentrated, although the net effect of the two on prices is insignificant. It appears, therefore, that, despite important distortions, hospital markets are not immune to standard competitive forces.

  17. Experimental demonstration of the importance of competition under disturbance

    PubMed Central

    Violle, Cyrille; Pu, Zhichao; Jiang, Lin

    2010-01-01

    Ecologists have long recognized the roles of competition and disturbance in shaping ecological communities, and the combinatorial effects of these two factors have been the subject of substantial ecological research. Nevertheless, it is still unclear whether competition remains as an important structuring force in habitats strongly influenced by disturbance. The conventional belief remains that the importance of competition decreases with increasing disturbance, but limited theory suggests otherwise. Using protist communities established in laboratory microcosms, we demonstrate that disturbance does not diminish the importance of competition. Interspecific competition significantly increased rates of species extinction over a broad disturbance gradient, and increasing disturbance intensities increased, rather than decreased, the tempo of competitive exclusion. This community-level pattern is linked to the species-level pattern that interspecific competition led to most frequent extinctions of each species at the highest level of disturbance that the species can tolerate. Consequently, despite a strong tradeoff between competitive ability and disturbance tolerance across the competing species, species diversity generally declined with disturbance. The consistent structuring role of competition throughout the disturbance gradient underscores the need to understand competitive interactions and their consequences even in highly disturbed habitats. PMID:20616069

  18. 47 CFR 73.5002 - Application and certification procedures; return of mutually exclusive applications not subject...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... information about the method of competitive bidding to be used and more detailed instructions on submitting... engineering data contained in the appropriate FCC form (FCC Form 301, FCC Form 346, or FCC Form 349... permitted to resolve their mutual exclusivities by making amendments to their engineering submissions...

  19. 47 CFR 73.5002 - Application and certification procedures; return of mutually exclusive applications not subject...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... information about the method of competitive bidding to be used and more detailed instructions on submitting... engineering data contained in the appropriate FCC form (FCC Form 301, FCC Form 346, or FCC Form 349... permitted to resolve their mutual exclusivities by making amendments to their engineering submissions...

  20. Children's Group Nous: Understanding and Applying Peer Exclusion Within and Between Groups

    ERIC Educational Resources Information Center

    Abrams, Dominic; Rutland, Adam; Pelletier, Joseph; Ferrell, Jennifer M.

    2009-01-01

    In Study 1, 167 English children aged 6-8 or 9-11 evaluated peer English or French soccer fans that were loyal or partially disloyal. In Study 2, 149 children aged 5-11 made judgments about generic inclusion norms between and within competitive groups. In both studies, children's understanding of intergroup inclusion/exclusion norms (group nous)…

  1. Children's Group Nous: Understanding and Applying Peer Exclusion Within and Between Groups

    ERIC Educational Resources Information Center

    Abrams, Dominic; Rutland, Adam; Pelletier, Joseph; Ferrell, Jennifer M.

    2009-01-01

    In Study 1, 167 English children aged 6-8 or 9-11 evaluated peer English or French soccer fans that were loyal or partially disloyal. In Study 2, 149 children aged 5-11 made judgments about generic inclusion norms between and within competitive groups. In both studies, children's understanding of intergroup inclusion/exclusion norms (group nous)…

  2. 76 FR 38122 - Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of an...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-29

    ... Department of the Army Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing..., Synthesis of and Methods of Use Thereof AGENCY: Department of the Army, DoD. ACTION: Notice. SUMMARY... represented by the Secretary of the Army, has rights to this invention. ADDRESSES: Commander, U.S....

  3. 78 FR 6814 - Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of an...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-31

    ... Department of the Army Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing... Epitopes AGENCY: Department of the Army, DoD. ACTION: Notice. SUMMARY: Announcement is made of the... September 22, 2006. The United States Government as represented by the Secretary of the Army has rights...

  4. 76 FR 38122 - Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of an...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-29

    ... Department of the Army Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing... Agents, Synthesis of and Methods of Use Thereof AGENCY: Department of the Army, DoD. ACTION: Notice... United States Government, as represented by the Secretary of the Army, has rights to this...

  5. 77 FR 2278 - Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of an...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Army Notice of Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of an Invention Concerning a Method and Device for Detection of Bioavailable Drug Concentration in a...

  6. Specialization and competition in dental health services.

    PubMed

    Grytten, Jostein; Skau, Irene

    2009-04-01

    The number of specialists within dental health services has increased over the last few years. This raises the issue of how the services should be organized and funded. We describe the effect of one way of organizing the services, which is by relying on competition. In Norway, some oral specialists face real competition with general dental practitioners for the same patients (prosthetists, periodontists and endodontists), while other specialists do not (orthodontists and oral surgeons). The latter specialists have skills that give them exclusive possibilities to practice their profession. We find that competition can be effective for the specialists who experience real competition with general dental practitioners for patients. In situations where real competition does not exist, specialists can obtain market power and raise their fees. Our results are based on an analysis of a representative set of data from general dental practitioners and specialists in Norway. The specialities in which practitioners can exercise market power raise challenges related to the type of public policy that can reduce this market power in an appropriate way, and without involving too large costs for the authorities. (c) 2008 John Wiley & Sons, Ltd.

  7. Approximate kernel competitive learning.

    PubMed

    Wu, Jian-Sheng; Zheng, Wei-Shi; Lai, Jian-Huang

    2015-03-01

    Kernel competitive learning has been successfully used to achieve robust clustering. However, kernel competitive learning (KCL) is not scalable for large scale data processing, because (1) it has to calculate and store the full kernel matrix that is too large to be calculated and kept in the memory and (2) it cannot be computed in parallel. In this paper we develop a framework of approximate kernel competitive learning for processing large scale dataset. The proposed framework consists of two parts. First, it derives an approximate kernel competitive learning (AKCL), which learns kernel competitive learning in a subspace via sampling. We provide solid theoretical analysis on why the proposed approximation modelling would work for kernel competitive learning, and furthermore, we show that the computational complexity of AKCL is largely reduced. Second, we propose a pseudo-parallelled approximate kernel competitive learning (PAKCL) based on a set-based kernel competitive learning strategy, which overcomes the obstacle of using parallel programming in kernel competitive learning and significantly accelerates the approximate kernel competitive learning for large scale clustering. The empirical evaluation on publicly available datasets shows that the proposed AKCL and PAKCL can perform comparably as KCL, with a large reduction on computational cost. Also, the proposed methods achieve more effective clustering performance in terms of clustering precision against related approximate clustering approaches.

  8. A perturbative approach to central exclusive production

    NASA Astrophysics Data System (ADS)

    Harland-Lang, L. A.; Khoze, V. A.; Ryskin, M. G.

    2015-02-01

    We review some selected results within the Durham model of central exclusive production. We present a detailed discussion of this theoretical approach for modeling exclusive processes and we briefly review some of its phenomenological applications.

  9. Exclusion Bounds for Extended Anyons

    NASA Astrophysics Data System (ADS)

    Larson, Simon; Lundholm, Douglas

    2017-08-01

    We introduce a rigorous approach to the many-body spectral theory of extended anyons, that is quantum particles confined to two dimensions that interact via attached magnetic fluxes of finite extent. Our main results are many-body magnetic Hardy inequalities and local exclusion principles for these particles, leading to estimates for the ground-state energy of the anyon gas over the full range of the parameters. This brings out further non-trivial aspects in the dependence on the anyonic statistics parameter, and also gives improvements in the ideal (non-extended) case.

  10. Approximating spatially exclusive invasion processes.

    PubMed

    Ross, Joshua V; Binder, Benjamin J

    2014-05-01

    A number of biological processes, such as invasive plant species and cell migration, are composed of two key mechanisms: motility and reproduction. Due to the spatially exclusive interacting behavior of these processes a cellular automata (CA) model is specified to simulate a one-dimensional invasion process. Three (independence, Poisson, and 2D-Markov chain) approximations are considered that attempt to capture the average behavior of the CA. We show that our 2D-Markov chain approximation accurately predicts the state of the CA for a wide range of motility and reproduction rates.

  11. 40 CFR 1508.4 - Categorical exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Categorical exclusion. 1508.4 Section 1508.4 Protection of Environment COUNCIL ON ENVIRONMENTAL QUALITY TERMINOLOGY AND INDEX § 1508.4 Categorical exclusion. Categorical exclusion means a category of actions which do not individually...

  12. 5 CFR 582.103 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Exclusions. 582.103 Section 582.103 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS COMMERCIAL GARNISHMENT OF FEDERAL EMPLOYEES' PAY Purpose, Definitions, and Exclusions § 582.103 Exclusions. In determining the...

  13. 47 CFR 25.401 - Satellite DARS applications subject to competitive bidding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Satellite DARS applications subject to...) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Competitive Bidding Procedures for DARS § 25.401 Satellite DARS applications subject to competitive bidding. Mutually exclusive initial applications for...

  14. 47 CFR 25.401 - Satellite DARS applications subject to competitive bidding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Satellite DARS applications subject to...) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Competitive Bidding Procedures for DARS § 25.401 Satellite DARS applications subject to competitive bidding. Mutually exclusive initial applications for...

  15. 47 CFR 25.401 - Satellite DARS applications subject to competitive bidding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Satellite DARS applications subject to...) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Competitive Bidding Procedures for DARS § 25.401 Satellite DARS applications subject to competitive bidding. Mutually exclusive initial applications for...

  16. 47 CFR 25.401 - Satellite DARS applications subject to competitive bidding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Satellite DARS applications subject to...) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Competitive Bidding Procedures for DARS § 25.401 Satellite DARS applications subject to competitive bidding. Mutually exclusive initial applications for...

  17. 47 CFR 25.401 - Satellite DARS applications subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Satellite DARS applications subject to...) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Competitive Bidding Procedures for DARS § 25.401 Satellite DARS applications subject to competitive bidding. Mutually exclusive initial applications for...

  18. 47 CFR 22.228 - Cellular rural service area licenses subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular rural service area licenses subject to... Procedures § 22.228 Cellular rural service area licenses subject to competitive bidding. Mutually exclusive initial applications for Cellular Rural Service Area licenses are subject to competitive bidding. The...

  19. 47 CFR 1.2102 - Eligibility of applications for competitive bidding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... bidding. 1.2102 Section 1.2102 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Competitive Bidding Proceedings General Procedures § 1.2102 Eligibility of applications for competitive bidding. (a) Mutually exclusive initial applications are subject...

  20. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false 800 MHz SMR spectrum subject to competitive... Specialized Mobile Radio Service § 90.901 800 MHz SMR spectrum subject to competitive bidding. Mutually exclusive initial applications for 800 MHz band licenses in Spectrum Blocks A through V are subject...

  1. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false 800 MHz SMR spectrum subject to competitive... Specialized Mobile Radio Service § 90.901 800 MHz SMR spectrum subject to competitive bidding. Mutually exclusive initial applications for 800 MHz band licenses in Spectrum Blocks A through V are subject...

  2. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false 800 MHz SMR spectrum subject to competitive... Specialized Mobile Radio Service § 90.901 800 MHz SMR spectrum subject to competitive bidding. Mutually exclusive initial applications for 800 MHz band licenses in Spectrum Blocks A through V are subject...

  3. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false 800 MHz SMR spectrum subject to competitive... Specialized Mobile Radio Service § 90.901 800 MHz SMR spectrum subject to competitive bidding. Mutually exclusive initial applications for 800 MHz band licenses in Spectrum Blocks A through V are subject...

  4. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false 800 MHz SMR spectrum subject to competitive... Specialized Mobile Radio Service § 90.901 800 MHz SMR spectrum subject to competitive bidding. Mutually exclusive initial applications for 800 MHz band licenses in Spectrum Blocks A through V are subject...

  5. First Robotics Competition

    NASA Image and Video Library

    2010-03-06

    Members of team 2377, in red, from Chesapeake High School in Maryland, react following a match during the second day of competition at the First Robotics Competition, Saturday, March 6, 2010, in Washington. The student competition is called "For Inspiration and Recognition of Science and Technology", or FIRST. The program was founded in 1989 by Dean Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers)

  6. Four paths of competition

    SciTech Connect

    Studness, C.M.

    1995-05-01

    The financial community`s focus on utility competition has been riveted on the proceedings now in progress at state regulatory commissions. The fear that something immediately damaging will come out of these proceedings seems to have diminished in recent months, and the stock market has reacted favorably. However, regulatory developments are only one of four paths leading to competition; the others are the marketplace, the legislatures, and the courts. Each could play a critical role in the emergence of competition.

  7. Social exclusion decreases prosocial behavior.

    PubMed

    Twenge, Jean M; Baumeister, Roy F; DeWall, C Nathan; Ciarocco, Natalie J; Bartels, J Michael

    2007-01-01

    In 7 experiments, the authors manipulated social exclusion by telling people that they would end up alone later in life or that other participants had rejected them. Social exclusion caused a substantial reduction in prosocial behavior. Socially excluded people donated less money to a student fund, were unwilling to volunteer for further lab experiments, were less helpful after a mishap, and cooperated less in a mixed-motive game with another student. The results did not vary by cost to the self or by recipient of the help, and results remained significant when the experimenter was unaware of condition. The effect was mediated by feelings of empathy for another person but was not mediated by mood, state self-esteem, belongingness, trust, control, or self-awareness. The implication is that rejection temporarily interferes with emotional responses, thereby impairing the capacity for empathic understanding of others, and as a result, any inclination to help or cooperate with them is undermined. 2007 APA, all rights reserved

  8. Choreography of Ig allelic exclusion.

    PubMed

    Cedar, Howard; Bergman, Yehudit

    2008-06-01

    Allelic exclusion guarantees that each B or T cell only produces a single antigen receptor, and in this way contributes to immune diversity. This process is actually initiated in the early embryo when the immune receptor loci become asynchronously replicating in a stochastic manner with one early and one late allele in each cell. This distinct differential replication timing feature then serves an instructive mark that directs a series of allele-specific epigenetic events in the immune system, including programmed histone modification, nuclear localization and DNA demethylation that ultimately bring about preferred rearrangement on a single allele, and this decision is temporally stabilized by feedback mechanisms that inhibit recombination on the second allele. In principle, these same molecular components are also used for controlling monoallelic expression at other genomic loci, such as those carrying interleukins and olfactory receptor genes that require the choice of one gene out of a large array. Thus, allelic exclusion appears to represent a general epigenetic phenomenon that is modeled on the same basis as X chromosome inactivation.

  9. Exclusion Process with Slow Boundary

    NASA Astrophysics Data System (ADS)

    Baldasso, Rangel; Menezes, Otávio; Neumann, Adriana; Souza, Rafael R.

    2017-06-01

    We study the hydrodynamic and the hydrostatic behavior of the simple symmetric exclusion process with slow boundary. The term slow boundary means that particles can be born or die at the boundary sites, at a rate proportional to N^{-θ }, where θ > 0 and N is the scaling parameter. In the bulk, the particles exchange rate is equal to 1. In the hydrostatic scenario, we obtain three different linear profiles, depending on the value of the parameter θ ; in the hydrodynamic scenario, we obtain that the time evolution of the spatial density of particles, in the diffusive scaling, is given by the weak solution of the heat equation, with boundary conditions that depend on θ . If θ \\in (0,1), we get Dirichlet boundary conditions, (which is the same behavior if θ =0, see Farfán in Hydrostatics, statical and dynamical large deviations of boundary driven gradient symmetric exclusion processes, 2008); if θ =1, we get Robin boundary conditions; and, if θ \\in (1,∞), we get Neumann boundary conditions.

  10. Intramural Gymnastics Competition.

    ERIC Educational Resources Information Center

    Cornelius, William L.

    1981-01-01

    An intramural gymnastic competition, if properly organized, can foster student and community interest in gymnastics. Aspects of organization and essential preplanning include: directing, judging, scoring, and managing. (JN)

  11. The Coevolutionary Period of Wolbachia pipientis Infecting Drosophila ananassae and Its Impact on the Evolution of the Host Germline Stem Cell Regulating Genes

    PubMed Central

    Choi, Jae Young; Aquadro, Charles F.

    2014-01-01

    The endosymbiotic bacteria Wolbachia pipientis is known to infect a wide range of arthropod species yet less is known about the coevolutionary history it has with its hosts. Evidence of highly identical W. pipientis strains in evolutionary divergent hosts suggests horizontal transfer between hosts. For example, Drosophila ananassae is infected with a W. pipientis strain that is nearly identical in sequence to a strain that infects both D. simulans and D. suzukii, suggesting recent horizontal transfer among these three species. However, it is unknown whether the W. pipientis strain had recently invaded all three species or a more complex infectious dynamic underlies the horizontal transfers. Here, we have examined the coevolutionary history of D. ananassae and its resident W. pipientis to infer its period of infection. Phylogenetic analysis of D. ananassae mitochondrial DNA and W. pipientis DNA sequence diversity revealed the current W. pipientis infection is not recent. In addition, we examined the population genetics and molecular evolution of several germline stem cell (GSC) regulating genes of D. ananassae. These studies reveal significant evidence of recent and long-term positive selection at stonewall in D. ananassae, whereas pumillio showed patterns of variation consistent with only recent positive selection. Previous studies had found evidence for adaptive evolution of two key germline differentiation genes, bag of marbles (bam) and benign gonial cell neoplasm (bgcn), in D. melanogaster and D. simulans and proposed that the adaptive evolution at these two genes was driven by arms race between the host GSC and W. pipientis. However, we did not find any statistical departures from a neutral model of evolution for bam and bgcn in D. ananassae despite our new evidence that this species has been infected with W. pipientis for a period longer than the most recent infection in D. melanogaster. In the end, analyzing the GSC regulating genes individually showed two

  12. The coevolutionary period of Wolbachia pipientis infecting Drosophila ananassae and its impact on the evolution of the host germline stem cell regulating genes.

    PubMed

    Choi, Jae Young; Aquadro, Charles F

    2014-09-01

    The endosymbiotic bacteria Wolbachia pipientis is known to infect a wide range of arthropod species yet less is known about the coevolutionary history it has with its hosts. Evidence of highly identical W. pipientis strains in evolutionary divergent hosts suggests horizontal transfer between hosts. For example, Drosophila ananassae is infected with a W. pipientis strain that is nearly identical in sequence to a strain that infects both D. simulans and D. suzukii, suggesting recent horizontal transfer among these three species. However, it is unknown whether the W. pipientis strain had recently invaded all three species or a more complex infectious dynamic underlies the horizontal transfers. Here, we have examined the coevolutionary history of D. ananassae and its resident W. pipientis to infer its period of infection. Phylogenetic analysis of D. ananassae mitochondrial DNA and W. pipientis DNA sequence diversity revealed the current W. pipientis infection is not recent. In addition, we examined the population genetics and molecular evolution of several germline stem cell (GSC) regulating genes of D. ananassae. These studies reveal significant evidence of recent and long-term positive selection at stonewall in D. ananassae, whereas pumillio showed patterns of variation consistent with only recent positive selection. Previous studies had found evidence for adaptive evolution of two key germline differentiation genes, bag of marbles (bam) and benign gonial cell neoplasm (bgcn), in D. melanogaster and D. simulans and proposed that the adaptive evolution at these two genes was driven by arms race between the host GSC and W. pipientis. However, we did not find any statistical departures from a neutral model of evolution for bam and bgcn in D. ananassae despite our new evidence that this species has been infected with W. pipientis for a period longer than the most recent infection in D. melanogaster. In the end, analyzing the GSC regulating genes individually showed two

  13. Exclusive Dijet production from CDF2LHC

    SciTech Connect

    Gallinaro, Michele; /Rockefeller U.

    2005-04-01

    Exclusive dijet production at the Tevatron can be used as a benchmark to establish predictions on exclusive diffractive Higgs production, a process with a much smaller cross section. Exclusive dijet production in Double Pomeron Exchange processes, including diffractive Higgs production with measurements at the Tevatron and predictions for the Large Hadron Collider are presented. Using new data from the Tevatron and dedicated diffractive triggers, no excess over a smooth falling distribution for exclusive dijet events could be found. Upper limits on the exclusive dijet production cross section are presented and compared to current theoretical predictions.

  14. Limiting similarity of competitive species and demographic stochasticity.

    PubMed

    Zheng, Xiu-Deng; Deng, Ling-Ling; Qiang, Wei-Ya; Cressman, Ross; Tao, Yi

    2017-04-01

    The limiting similarity of competitive species and its relationship with the competitive exclusion principle is still one of the most important concepts in ecology. In the 1970s, May [R. M. May, Stability and Complexity in Model Ecosystems (Princeton University, Princeton, NJ, 1973)] developed a concise theoretical framework to investigate the limiting similarity of competitive species. His theoretical results show that no limiting similarity threshold of competitive species can be identified in the deterministic model system whereby species more similar than this threshold never coexist. Theoretically, for competitive species coexisting in an unvarying environment, deterministic interspecific interactions and demographic stochasticity can be considered two sides of a coin. To investigate how the "tension" between these two forces affects the coexistence of competing species, a simple two-species competitive system based only on May's model system is transformed into an equivalent replicator equation. The effect of demographic stochasticity on the system stability is measured by the expected drift of the Lyapunov function. Our main results show that the limiting similarity of competitive species should not be considered to be an absolute measure. Specifically, very similar competitive species should be able to coexist in an environment with a high productivity level but big differences between competitive species should be necessary in an ecosystem with a low productivity level.

  15. The quick and the dead? Sperm competition and sexual conflict in sea.

    PubMed

    Bode, Michael; Marshall, Dustin J

    2007-11-01

    Our view of sperm competition is largely shaped by game-theoretic models based on external fertilizers. External fertilization is of particular interest as it is the ancestral mode of reproduction and as such, relevant to the evolution and maintenance of anisogamy (i.e., large eggs and tiny, numerous sperm). Current game-theoretic models have been invaluable in generating predictions of male responses to sperm competition in a range of internal fertilizers but these models are less relevant to marine broadcast spawners, the most common and archetypal external fertilizers. Broadcast spawners typically have incomplete fertilization due to sperm limitation and/or polyspermy (too many sperm), but the effects of incomplete (<100% fertilization rates) fertilization on game-theoretic predictions are unclear particular with regards to polyspermy. We show that incorporating the effects of sperm concentration on fertilization success changes the predictions of a classic game-theoretic model, dramatically reversing the relationship between sperm competition and the evolutionarily stable sperm release strategy. Furthermore, our results suggest that male and female broadcast spawners are likely to be in conflict at both ends of the sperm environment continuum rather than only in conditions of excess sperm as previously thought. Across the majority of the parameter space we explored, males release either too little to too much sperm for females to achieve complete fertilization. This conflict could result in a coevolutionary race that may have led to the evolution of internal fertilization in marine organisms.

  16. Maternal Competition in Women.

    PubMed

    Linney, Catherine; Korologou-Linden, Laurel; Campbell, Anne

    2017-03-01

    We examined maternal competition, an unexplored form of competition between women. Given women's high investment in offspring and mothers' key role in shaping their reproductive, social, and cultural success as adults, we might expect to see maternal competition between women as well as mate competition. Predictions about the effect of maternal characteristics (age, relationship status, educational background, number of children, investment in the mothering role) and child variables (age, sex) were drawn from evolutionary theory and sociological research. Mothers of primary school children (in two samples: N = 210 and 169) completed a series of questionnaires. A novel nine-item measure of maternal competitive behavior (MCQ) and two subscales assessing Covert (MCQ-C) and Face-to-Face (MCQ-FF) forms of competition were developed using confirmatory factor analysis. Competitiveness (MCQ score) was predicted by maternal investment, single motherhood, fewer children, and (marginally) child's older age. The effect of single motherhood (but not other predictors) was partially mediated by greater maternal investment. In response to a scenario of their child underperforming relative to their peers, a mother's competitive distress was a positive function of the importance she ascribed to their success and her estimation of her child's ability. Her competitive distress was highly correlated with the distress she attributed to a female friend, hinting at bidirectional dyadic effects. Qualitative responses indicated that nonspecific bragging and boasting about academic achievements were the most common irritants. Although 40% of women were angered or annoyed by such comments, less than 5% endorsed a direct hostile response. Instead, competitive mothers were conversationally shunned and rejected as friends. We suggest that the interdependence of mothers based on reciprocal childcare has supported a culture of egalitarianism that is violated by explicit competitiveness.

  17. Incorporating cultural beliefs in promoting exclusive breastfeeding

    PubMed Central

    Reinsma, Kathryn; Bolima, Nancy; Fonteh, Florence; Okwen, Patrick; Yota, Daniel; Montgomery, Susanne

    2015-01-01

    Introduction Since 2003, the World Health Organization has recommended exclusive breastfeeding for the first 6 months of life. In the Northwest region of Cameroon approximately 90% of women initiate breastfeeding, yet only 34% of these women exclusively breastfeed for the recommended six months. Aim To determine influences on women’s exclusive breastfeeding practices. Methods Semi-structured interviews were conducted with six women and six men followed by focus group discussions with three groups of women and three groups of men in the Kumbo West Health District, Northwest region, Cameroon. All participants were selected using theoretical sampling to assure triangulation. Results Three themes emerged that influence exclusive breastfeeding practices: woman’s readiness to exclusively breastfeed; cultural influences towards exclusive breastfeeding; and perceived constraints to exclusive breastfeeding. Conclusion These emergent themes were used to create a theoretical framework that is useful for developing a breastfeeding health education intervention in non-Western settings. PMID:26973717

  18. Seed Removal Increased by Scramble Competition with an Invasive Species

    PubMed Central

    Minor, Rebecca L.; Koprowski, John L.

    2015-01-01

    Competition for seeds has a major influence on the evolution of granivores and the plants on which they rely. The complexity of interactions and coevolutionary relationships vary across forest types. The introduction of non-native granivores has considerable potential to alter seed dispersal dynamics. Non-native species are a major cause of endangerment for native species, but the mechanisms are often unclear. As biological invasions continue to rise, it is important to understand mechanisms to build up strategies to mitigate the threat. Our field experiment quantified the impact of introduced Abert’s squirrels (Sciurus aberti) on rates of seed removal within the range of critically endangered Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis), which consumes similar foods. In the presence of invasive Abert’s squirrels, the time cones were removed was faster than when the invasive was excluded, accounting for a median removal time of cones available to red and Abert’s squirrels that is 32.8% less than that of cones available only to the rare native red squirrels. Moreover, in the presence of Abert’s squirrels, removal rates are higher at great distance from a territorial red squirrel larderhoard and in more open portions of the forest, which suggests differential patterns of seed dispersal. The impact on food availability as a result of cone removal by Abert’s squirrels suggests the potential of food competition as a mechanism of endangerment for the Mount Graham red squirrel. Furthermore, the magnitude and differential spatial patterns of seed removal suggest that non-native granivores may have impacts on forest regeneration and structure. PMID:26650073

  19. Seed Removal Increased by Scramble Competition with an Invasive Species.

    PubMed

    Minor, Rebecca L; Koprowski, John L

    2015-01-01

    Competition for seeds has a major influence on the evolution of granivores and the plants on which they rely. The complexity of interactions and coevolutionary relationships vary across forest types. The introduction of non-native granivores has considerable potential to alter seed dispersal dynamics. Non-native species are a major cause of endangerment for native species, but the mechanisms are often unclear. As biological invasions continue to rise, it is important to understand mechanisms to build up strategies to mitigate the threat. Our field experiment quantified the impact of introduced Abert's squirrels (Sciurus aberti) on rates of seed removal within the range of critically endangered Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis), which consumes similar foods. In the presence of invasive Abert's squirrels, the time cones were removed was faster than when the invasive was excluded, accounting for a median removal time of cones available to red and Abert's squirrels that is 32.8% less than that of cones available only to the rare native red squirrels. Moreover, in the presence of Abert's squirrels, removal rates are higher at great distance from a territorial red squirrel larderhoard and in more open portions of the forest, which suggests differential patterns of seed dispersal. The impact on food availability as a result of cone removal by Abert's squirrels suggests the potential of food competition as a mechanism of endangerment for the Mount Graham red squirrel. Furthermore, the magnitude and differential spatial patterns of seed removal suggest that non-native granivores may have impacts on forest regeneration and structure.

  20. Long-range RNA pairings contribute to mutually exclusive splicing

    PubMed Central

    Yue, Yuan; Yang, Yun; Dai, Lanzhi; Cao, Guozheng; Chen, Ran; Hong, Weiling; Liu, Baoping; Shi, Yang; Meng, Yijun; Shi, Feng; Xiao, Mu; Jin, Yongfeng

    2016-01-01

    Mutually exclusive splicing is an important means of increasing the protein repertoire, by which the Down's syndrome cell adhesion molecule (Dscam) gene potentially generates 38,016 different isoforms in Drosophila melanogaster. However, the regulatory mechanisms remain obscure due to the complexity of the Dscam exon cluster. Here, we reveal a molecular model for the regulation of the mutually exclusive splicing of the serpent pre-mRNA based on competition between upstream and downstream RNA pairings. Such dual RNA pairings confer fine tuning of the inclusion of alternative exons. Moreover, we demonstrate that the splicing outcome of alternative exons is mediated in relative pairing strength-correlated mode. Combined comparative genomics analysis and experimental evidence revealed similar bidirectional structural architectures in exon clusters 4 and 9 of the Dscam gene. Our findings provide a novel mechanistic framework for the regulation of mutually exclusive splicing and may offer potentially applicable insights into long-range RNA–RNA interactions in gene regulatory networks. PMID:26554032

  1. Long-range RNA pairings contribute to mutually exclusive splicing.

    PubMed

    Yue, Yuan; Yang, Yun; Dai, Lanzhi; Cao, Guozheng; Chen, Ran; Hong, Weiling; Liu, Baoping; Shi, Yang; Meng, Yijun; Shi, Feng; Xiao, Mu; Jin, Yongfeng

    2016-01-01

    Mutually exclusive splicing is an important means of increasing the protein repertoire, by which the Down's syndrome cell adhesion molecule (Dscam) gene potentially generates 38,016 different isoforms in Drosophila melanogaster. However, the regulatory mechanisms remain obscure due to the complexity of the Dscam exon cluster. Here, we reveal a molecular model for the regulation of the mutually exclusive splicing of the serpent pre-mRNA based on competition between upstream and downstream RNA pairings. Such dual RNA pairings confer fine tuning of the inclusion of alternative exons. Moreover, we demonstrate that the splicing outcome of alternative exons is mediated in relative pairing strength-correlated mode. Combined comparative genomics analysis and experimental evidence revealed similar bidirectional structural architectures in exon clusters 4 and 9 of the Dscam gene. Our findings provide a novel mechanistic framework for the regulation of mutually exclusive splicing and may offer potentially applicable insights into long-range RNA-RNA interactions in gene regulatory networks. © 2015 Yue et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  2. Competitiveness, Technology and Skills.

    ERIC Educational Resources Information Center

    Lall, Sanjaya

    This document examines competitiveness in the developing world. Chapters 1 through 3, which are largely conceptual, examine the following topics: the concept of competitiveness and why it is important; market-stimulating technology policies in developing countries, and the relationship between import liberalization and industrial performance.…

  3. Competition: Was Kohn Right?

    ERIC Educational Resources Information Center

    Shields, David Light; Bredemeier, Brenda Light

    2010-01-01

    Alfie Kohn made the case for competition being destructive to education. The truth may be that there are two separate ways to contest: true competition, which is a healthy desire to excel, and decompetition, which is the unhealthy desire merely to beat the opponent. Decompetition leads to the ills that Kohn enumerated. Educators should teach their…

  4. Competition: Was Kohn Right?

    ERIC Educational Resources Information Center

    Shields, David Light; Bredemeier, Brenda Light

    2010-01-01

    Alfie Kohn made the case for competition being destructive to education. The truth may be that there are two separate ways to contest: true competition, which is a healthy desire to excel, and decompetition, which is the unhealthy desire merely to beat the opponent. Decompetition leads to the ills that Kohn enumerated. Educators should teach their…

  5. Competitiveness, Technology and Skills.

    ERIC Educational Resources Information Center

    Lall, Sanjaya

    This document examines competitiveness in the developing world. Chapters 1 through 3, which are largely conceptual, examine the following topics: the concept of competitiveness and why it is important; market-stimulating technology policies in developing countries, and the relationship between import liberalization and industrial performance.…

  6. Reflections on cell competition.

    PubMed

    Baillon, Ludovic; Basler, Konrad

    2014-08-01

    Cell competition is a process by which otherwise viable cells are actively eliminated due to the presence of more competitive cells. It is a conserved phenomenon and occurs in various developmental and experimental contexts. Competitive elimination represents a safeguard mechanism that potentiates animal development. However, the process can also be hijacked, for example, by cancer cells to promote and sustain malignancy. One of the challenges facing the field is that the term "cell competition" is used to describe a variety of phenomena whose relatedness is under debate. The goals of this review are to provide an overview of the literature on cell competition-like phenomena, highlight where there are discrepancies, and, when possible, provide alternative interpretations to reconcile the dissonance. Central to this is a comparison of the various models of cell competition. With our critical examination we seek to draw attention to future prospects in the field of cell competition. We believe that the elucidation of the interplay between loser and winner cells in the process of cell competition will provide new targets for the development of cancer therapeutics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Woody competition control

    Treesearch

    Robert F. Lowery

    1986-01-01

    Control of woody competition is necessary to maintain shortleaf pine (Pinus echinata Mill.) as an important component of natural stands and to maximize shortleaf pine plantation productivity in the Southeast. Competition control is key to maximizing timber production since growth is moisture-limited over much of its range. Volume growth gains of 40% have been reported...

  8. Central exclusive production at RHIC

    SciTech Connect

    Adamczyk, Leszek; Guryn, Włodek; Turnau, Jacek

    2014-11-10

    The present status and future plans of the physics program of Central Exclusive Production (CEP) at RHIC are described. The measurements are based on the detection of the forward protons from the Double Pomeron Exchange (DPE) process in the Roman Pot system and of the recoil system of charged particles from the DPE process measured in the STAR experiment’s Time Projection Chamber (TPC). The data described here were taken using polarized proton-proton collisions at ps = 200 GeV. The preliminary spectra of two pion and four pion invariant mass reconstructed by STAR TPC in central region of pseudo-rapidity | | < 1, are presented. Near future plans to take data with the current system at center-of-mass energy ps = 200 GeV and plans to upgrade the forward proton tagging sys- tem are presented. Also a possible addition of the Roman Pots to the sPHENIX detector is discussed.

  9. Hard Exclusive Reactions at Jlab

    SciTech Connect

    Kubarovsky, Valery P.

    2011-09-20

    Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out at Jefferson Lab. DVCS helicity--dependent and helicity--independent cross sections and beam spin asymmetries have been measured, as well as cross sections and asymmetries for the $\\pi^0$, $\\eta$, $\\rho^0$, $\\rho^+$, $\\omega$ and $\\phi$ for exclusive electroproduction. The data were taken in a wide kinematic range in $Q^2$=1--4.5 GeV$^2$, $x_B$=0.1--0.5, and $|t|$ up to 2 GeV$^2$. The presented results offer a unique opportunity to study the structure of the nucleon at the parton level as one has access to Bjorken $x_B$ and momentum transfer to the nucleon $t$ at the same time.

  10. Evaluation of water resources system vulnerability based on co-operative co-evolutionary genetic algorithm and projection pursuit model under the DPSIR framework

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Su, X. H.; Wang, M. H.; Li, Z. Y.; Li, E. K.; Xu, X.

    2017-08-01

    Water resources vulnerability control management is essential because it is related to the benign evolution of socio-economic, environmental and water resources system. Research on water resources system vulnerability is helpful to realization of water resources sustainable utilization. In this study, the DPSIR framework of driving forces-pressure–state–impact-response was adopted to construct the evaluation index system of water resources system vulnerability. Then the co-evolutionary genetic algorithm and projection pursuit were used to establish evaluation model of water resources system vulnerability. Tengzhou City in Shandong Province was selected as a study area. The system vulnerability was analyzed in terms of driving forces, pressure, state, impact and response on the basis of the projection value calculated by the model. The results show that the five components all belong to vulnerability Grade II, the vulnerability degree of impact and state were higher than other components due to the fierce imbalance in supply-demand and the unsatisfied condition of water resources utilization. It is indicated that the influence of high speed socio-economic development and the overuse of the pesticides have already disturbed the benign development of water environment to some extents. While the indexes in response represented lower vulnerability degree than the other components. The results of the evaluation model are coincident with the status of water resources system in the study area, which indicates that the model is feasible and effective.

  11. Co-evolutionary patterns and diversification of ant-fungus associations in the asexual fungus-farming ant Mycocepurus smithii in Panama.

    PubMed

    Kellner, K; Fernández-Marín, H; Ishak, H D; Sen, R; Linksvayer, T A; Mueller, U G

    2013-06-01

    Partner fidelity through vertical symbiont transmission is thought to be the primary mechanism stabilizing cooperation in the mutualism between fungus-farming (attine) ants and their cultivated fungal symbionts. An alternate or additional mechanism could be adaptive partner or symbiont choice mediating horizontal cultivar transmission or de novo domestication of free-living fungi. Using microsatellite genotyping for the attine ant Mycocepurus smithii and ITS rDNA sequencing for fungal cultivars, we provide the first detailed population genetic analysis of local ant-fungus associations to test for the relative importance of vertical vs. horizontal transmission in a single attine species. M. smithii is the only known asexual attine ant, and it is furthermore exceptional because it cultivates a far greater cultivar diversity than any other attine ant. Cultivar switching could permit the ants to re-acquire cultivars after garden loss, to purge inferior cultivars that are locally mal-adapted or that accumulated deleterious mutations under long-term asexuality. Compared to other attine ants, symbiont choice and local adaptation of ant-fungus combinations may play a more important role than partner-fidelity feedback in the co-evolutionary process of M. smithii and its fungal symbionts.

  12. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

    2002-01-01

    This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

  13. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

    2002-01-01

    This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

  14. 7 CFR 520.5 - Categorical exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... implementation which are related to routine activities such as personnel, organizational changes or similar... agency. (c) Exceptions to categorical exclusions. An environmental assessment shall be prepared for an...

  15. Central exclusive production at RHIC

    DOE PAGES

    Adamczyk, Leszek; Guryn, Włodek; Turnau, Jacek

    2014-11-10

    The present status and future plans of the physics program of Central Exclusive Production (CEP) at RHIC are described. The measurements are based on the detection of the forward protons from the Double Pomeron Exchange (DPE) process in the Roman Pot system and of the recoil system of charged particles from the DPE process measured in the STAR experiment’s Time Projection Chamber (TPC). The data described here were taken using polarized proton-proton collisions at ps = 200 GeV. The preliminary spectra of two pion and four pion invariant mass reconstructed by STAR TPC in central region of pseudo-rapidity | |more » < 1, are presented. Near future plans to take data with the current system at center-of-mass energy ps = 200 GeV and plans to upgrade the forward proton tagging sys- tem are presented. Also a possible addition of the Roman Pots to the sPHENIX detector is discussed.« less

  16. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    Energy levels are high in the RoboPit as teams prepare for NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. arel using their mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  17. A Study in Competition

    ERIC Educational Resources Information Center

    Payne, Therese Anne

    1973-01-01

    Describes a microbiological experiment designed to study the competition between two species of bacteria. Experimental procedures and data obtained in conducting this experiment are provided, together with a discussion of the results. (JR)

  18. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-23

    College team members watch a live display of their mining robots during test runs in the mining arena at NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. will use their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  19. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    A robotic miner digs in the mining arena during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  20. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-23

    College team members prepare to enter the robotic mining arena for a test run during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. will use their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  1. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    The robotic miner from Mississippi State University digs in the mining arena during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  2. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-23

    Team Raptor members from the University of North Dakota College of Engineering and Mines check their robot, named "Marsbot," in the RoboPit at NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. will use their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  3. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    Twin mining robots from the University of Iowa dig in a supersized sandbox filled with BP-1, or simulated Martian soil, during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  4. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-23

    Team members from Purdue University prepare their uniquely-designed robot miner in the RoboPit at NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. will use their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  5. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-23

    NASA Kennedy Space Center Director Bob Cabana welcomes participants to the agency's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. will use their mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  6. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    Team members from the New York University Tandon School of Engineering transport their robot to the mining arena during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  7. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    Team members from West Virginia University prepare their mining robot for a test run in a giant sandbox before their scheduled mining run in the arena during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  8. 2017 Robotic Mining Competition

    NASA Image and Video Library

    2017-05-24

    Derrick Matthews, left, with Kennedy Space Center's Communication and Public Engagement Directorate, and Kurt Leucht, event emcee, provide commentary at the mining arena during NASA's 8th Annual Robotic Mining Competition at the Kennedy Space Center Visitor Complex in Florida. More than 40 student teams from colleges and universities around the U.S. are using their uniquely-designed mining robots to dig in a supersized sandbox filled with BP-1, or simulated Martian soil, and participate in other competition requirements. The Robotic Mining Competition is a NASA Human Exploration and Operations Mission Directorate project designed to encourage students in science, technology, engineering and math, or STEM fields. The project provides a competitive environment to foster innovative ideas and solutions that could be used on NASA's Journey to Mars.

  9. An ecocultural model predicts Neanderthal extinction through competition with modern humans

    PubMed Central

    Gilpin, William; Feldman, Marcus W.; Aoki, Kenichi

    2016-01-01

    Archaeologists argue that the replacement of Neanderthals by modern humans was driven by interspecific competition due to a difference in culture level. To assess the cogency of this argument, we construct and analyze an interspecific cultural competition model based on the Lotka−Volterra model, which is widely used in ecology, but which incorporates the culture level of a species as a variable interacting with population size. We investigate the conditions under which a difference in culture level between cognitively equivalent species, or alternatively a difference in underlying learning ability, may produce competitive exclusion of a comparatively (although not absolutely) large local Neanderthal population by an initially smaller modern human population. We find, in particular, that this competitive exclusion is more likely to occur when population growth occurs on a shorter timescale than cultural change, or when the competition coefficients of the Lotka−Volterra model depend on the difference in the culture levels of the interacting species. PMID:26831111

  10. An ecocultural model predicts Neanderthal extinction through competition with modern humans.

    PubMed

    Gilpin, William; Feldman, Marcus W; Aoki, Kenichi

    2016-02-23

    Archaeologists argue that the replacement of Neanderthals by modern humans was driven by interspecific competition due to a difference in culture level. To assess the cogency of this argument, we construct and analyze an interspecific cultural competition model based on the Lotka-Volterra model, which is widely used in ecology, but which incorporates the culture level of a species as a variable interacting with population size. We investigate the conditions under which a difference in culture level between cognitively equivalent species, or alternatively a difference in underlying learning ability, may produce competitive exclusion of a comparatively (although not absolutely) large local Neanderthal population by an initially smaller modern human population. We find, in particular, that this competitive exclusion is more likely to occur when population growth occurs on a shorter timescale than cultural change, or when the competition coefficients of the Lotka-Volterra model depend on the difference in the culture levels of the interacting species.

  11. 2000 FIRST Robotics Competition

    NASA Technical Reports Server (NTRS)

    Purman, Richard

    2000-01-01

    The New Horizons Regional Education Center (NHREC) in Hampton, VA sought and received NASA funding to support its participation in the 2000 FIRST Robotics competition. FIRST, Inc. (For Inspiration and Recognition of Science and Technology) is an organization which encourages the application of creative science, math, and computer science principles to solve real-world engineering problems. The FIRST competition is an international engineering contest featuring high school, government, and business partnerships.

  12. First Robotics Competition

    NASA Image and Video Library

    2010-03-06

    A student member of the team 768 "Technowarriors" from Woodlawn High School in Maryland runs a controller while competing in a match during the second day of the First Robotics Competition, Saturday, March 6, 2010, in Washington. The student competition is called "For Inspiration and Recognition of Science and Technology", or FIRST. The program was founded in 1989 by Dean Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers)

  13. 2000 FIRST Robotics Competition

    NASA Technical Reports Server (NTRS)

    Purman, Richard

    2000-01-01

    The New Horizons Regional Education Center (NHREC) in Hampton, VA sought and received NASA funding to support its participation in the 2000 FIRST Robotics competition. FIRST, Inc. (For Inspiration and Recognition of Science and Technology) is an organization which encourages the application of creative science, math, and computer science principles to solve real-world engineering problems. The FIRST competition is an international engineering contest featuring high school, government, and business partnerships.

  14. First Robotics Competition

    NASA Image and Video Library

    2010-03-06

    Robots vie for position during the second day of the First Robotics Competition, Saturday, March 6, 2010, in Washington. The student competition is called "For Inspiration and Recognition of Science and Technology", or FIRST. The program was founded in 1989 by Dean Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers)

  15. Competition for land.

    PubMed

    Smith, Pete; Gregory, Peter J; van Vuuren, Detlef; Obersteiner, Michael; Havlík, Petr; Rounsevell, Mark; Woods, Jeremy; Stehfest, Elke; Bellarby, Jessica

    2010-09-27

    A key challenge for humanity is how a future global population of 9 billion can all be fed healthily and sustainably. Here, we review how competition for land is influenced by other drivers and pressures, examine land-use change over the past 20 years and consider future changes over the next 40 years. Competition for land, in itself, is not a driver affecting food and farming in the future, but is an emergent property of other drivers and pressures. Modelling studies suggest that future policy decisions in the agriculture, forestry, energy and conservation sectors could have profound effects, with different demands for land to supply multiple ecosystem services usually intensifying competition for land in the future. In addition to policies addressing agriculture and food production, further policies addressing the primary drivers of competition for land (population growth, dietary preference, protected areas, forest policy) could have significant impacts in reducing competition for land. Technologies for increasing per-area productivity of agricultural land will also be necessary. Key uncertainties in our projections of competition for land in the future relate predominantly to uncertainties in the drivers and pressures within the scenarios, in the models and data used in the projections and in the policy interventions assumed to affect the drivers and pressures in the future.

  16. Competition for land

    PubMed Central

    Smith, Pete; Gregory, Peter J.; van Vuuren, Detlef; Obersteiner, Michael; Havlík, Petr; Rounsevell, Mark; Woods, Jeremy; Stehfest, Elke; Bellarby, Jessica

    2010-01-01

    A key challenge for humanity is how a future global population of 9 billion can all be fed healthily and sustainably. Here, we review how competition for land is influenced by other drivers and pressures, examine land-use change over the past 20 years and consider future changes over the next 40 years. Competition for land, in itself, is not a driver affecting food and farming in the future, but is an emergent property of other drivers and pressures. Modelling studies suggest that future policy decisions in the agriculture, forestry, energy and conservation sectors could have profound effects, with different demands for land to supply multiple ecosystem services usually intensifying competition for land in the future. In addition to policies addressing agriculture and food production, further policies addressing the primary drivers of competition for land (population growth, dietary preference, protected areas, forest policy) could have significant impacts in reducing competition for land. Technologies for increasing per-area productivity of agricultural land will also be necessary. Key uncertainties in our projections of competition for land in the future relate predominantly to uncertainties in the drivers and pressures within the scenarios, in the models and data used in the projections and in the policy interventions assumed to affect the drivers and pressures in the future. PMID:20713395

  17. Exclusive Hyperon Production at CLAS

    NASA Astrophysics Data System (ADS)

    Carman, Daniel

    2009-10-01

    This talk will provide an overview of the exclusive hyperon production experiments being carried out by the CLAS Collaboration at Jefferson Laboratory. The program is designed to measure cross sections and a complete set of beam, target, and recoil hyperon polarization observables for both Kλ and Kσ final states with beam energies up to 6 GeV. These data will span a broad kinematic range in momentum transfer Q^2 and invariant energy W, and nearly the full center-of-mass angular range of the kaon. Analyses of data on both proton and neutron targets are underway or planned for the near future involving polarized beams (longitudinally polarized electrons, circularly and linearly polarized photons) and polarized targets (longitudinally and transversely polarized). The main goal of this series of measurements is to provide precision data needed to disentangle the resonant and non-resonant amplitudes in the intermediate state to uncover baryon resonances that couple to the strangeness channels (N^* ->Kλ, Kσ, &*circ;->Kσ). This will improve our understanding of the nucleon excitation spectrum, and hence, probe the effective degrees of freedom of the nucleon. These data will also serve to improve our understanding of the dynamics underlying strangeness production in general. Over the next several years it is expected that a full coupled-channels analysis, including hadroproduction data, as well as data with both real and virtual photons, will be completed by several groups, including the Excited Baryon Analysis Center (EBAC) at Jefferson Laboratory. The precision data from CLAS will be a crucial input for these analyses. Within the next five years, the CLAS facility will be significantly upgraded for use with the higher-energy electron beams available with the 12-GeV Jefferson Laboratory energy upgrade. The future of the strangeness physics program with the new CLAS12 facility will be highlighted.

  18. Plant Community Richness Mediates Inhibitory Interactions and Resource Competition between Streptomyces and Fusarium Populations in the Rhizosphere.

    PubMed

    Essarioui, Adil; LeBlanc, Nicholas; Kistler, Harold C; Kinkel, Linda L

    2017-01-05

    Plant community characteristics impact rhizosphere Streptomyces nutrient competition and antagonistic capacities. However, the effects of Streptomyces on, and their responses to, coexisting microorganisms as a function of plant host or plant species richness have received little attention. In this work, we characterized antagonistic activities and nutrient use among Streptomyces and Fusarium from the rhizosphere of Andropogon gerardii (Ag) and Lespedeza capitata (Lc) plants growing in communities of 1 (monoculture) or 16 (polyculture) plant species. Streptomyces from monoculture were more antagonistic against Fusarium than those from polyculture. In contrast, Fusarium isolates from polyculture had greater inhibitory capacities against Streptomyces than isolates from monoculture. Although Fusarium isolates had on average greater niche widths, the collection of Streptomyces isolates in total used a greater diversity of nutrients for growth. Plant richness, but not plant host, influenced the potential for resource competition between the two taxa. Fusarium isolates had greater niche overlap with Streptomyces in monoculture than polyculture, suggesting greater potential for Fusarium to competitively challenge Streptomyces in monoculture plant communities. In contrast, Streptomyces had greater niche overlap with Fusarium in polyculture than monoculture, suggesting that Fusarium experiences greater resource competition with Streptomyces in polyculture than monoculture. These patterns of competitive and inhibitory phenotypes among Streptomyces and Fusarium populations are consistent with selection for Fusarium-antagonistic Streptomyces populations in the presence of strong Fusarium resource competition in plant monocultures. Similarly, these results suggest selection for Streptomyces-inhibitory Fusarium populations in the presence of strong Streptomyces resource competition in more diverse plant communities. Thus, landscape-scale variation in plant species richness may be

  19. Healthy Competition and Unsound Comparison: Reforming Educational Competition in Singapore

    ERIC Educational Resources Information Center

    Christensen, Søren

    2015-01-01

    It is frequently claimed that the "competition state" responds to external competition by making competition increasingly central to its internal processes as well. This article discusses education reform in Singapore as departing from the opposite position. In Singapore "excessive" competition in education is now targeted by…

  20. Healthy Competition and Unsound Comparison: Reforming Educational Competition in Singapore

    ERIC Educational Resources Information Center

    Christensen, Søren

    2015-01-01

    It is frequently claimed that the "competition state" responds to external competition by making competition increasingly central to its internal processes as well. This article discusses education reform in Singapore as departing from the opposite position. In Singapore "excessive" competition in education is now targeted by…

  1. 47 CFR 76.107 - Exclusivity contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Exclusivity contracts. 76.107 Section 76.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports Blackout...

  2. 47 CFR 76.107 - Exclusivity contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Exclusivity contracts. 76.107 Section 76.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports Blackout...

  3. 47 CFR 76.107 - Exclusivity contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Exclusivity contracts. 76.107 Section 76.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports Blackout...

  4. 12 CFR 229.42 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Exclusions. 229.42 Section 229.42 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM AVAILABILITY OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Collection of Checks § 229.42 Exclusions....

  5. 47 CFR 76.107 - Exclusivity contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Exclusivity contracts. 76.107 Section 76.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports...

  6. 47 CFR 76.107 - Exclusivity contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Exclusivity contracts. 76.107 Section 76.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports...

  7. 10 CFR 830.2 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Exclusions. 830.2 Section 830.2 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT § 830.2 Exclusions. This part does not apply to: (a) Activities that are... 1974, as amended; and (e) Activities related to the launch approval and actual launch of nuclear...

  8. 10 CFR 830.2 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Exclusions. 830.2 Section 830.2 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT § 830.2 Exclusions. This part does not apply to: (a) Activities that are... 1974, as amended; and (e) Activities related to the launch approval and actual launch of nuclear...

  9. 10 CFR 830.2 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Exclusions. 830.2 Section 830.2 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT § 830.2 Exclusions. This part does not apply to: (a) Activities that are... 1974, as amended; and (e) Activities related to the launch approval and actual launch of nuclear...

  10. 10 CFR 830.2 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Exclusions. 830.2 Section 830.2 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT § 830.2 Exclusions. This part does not apply to: (a) Activities that are... 1974, as amended; and (e) Activities related to the launch approval and actual launch of nuclear...

  11. 10 CFR 830.2 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Exclusions. 830.2 Section 830.2 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT § 830.2 Exclusions. This part does not apply to: (a) Activities that are... 1974, as amended; and (e) Activities related to the launch approval and actual launch of nuclear...

  12. 47 CFR 73.232 - Territorial exclusivity.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Territorial exclusivity. 73.232 Section 73.232 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.232 Territorial exclusivity. No licensee of an FM broadcast station shall have...

  13. 47 CFR 73.232 - Territorial exclusivity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Territorial exclusivity. 73.232 Section 73.232 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.232 Territorial exclusivity. No licensee of an FM broadcast station shall have...

  14. 18 CFR 1308.3 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 2 2011-04-01 2011-04-01 false Exclusions. 1308.3 Section 1308.3 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES General Matters § 1308.3 Exclusions. (a) This part does not apply to any TVA contract which does not...

  15. 18 CFR 1308.3 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 2 2014-04-01 2014-04-01 false Exclusions. 1308.3 Section 1308.3 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES General Matters § 1308.3 Exclusions. (a) This part does not apply to any TVA contract which does not...

  16. 18 CFR 1308.3 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Exclusions. 1308.3 Section 1308.3 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES General Matters § 1308.3 Exclusions. (a) This part does not apply to any TVA contract which does not...

  17. 18 CFR 1308.3 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Exclusions. 1308.3 Section 1308.3 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES General Matters § 1308.3 Exclusions. (a) This part does not apply to any TVA contract which does not...

  18. 18 CFR 1308.3 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Exclusions. 1308.3 Section 1308.3 Conservation of Power and Water Resources TENNESSEE VALLEY AUTHORITY CONTRACT DISPUTES General Matters § 1308.3 Exclusions. (a) This part does not apply to any TVA contract which does not...

  19. Exclusion from School and Recognition of Difference

    ERIC Educational Resources Information Center

    McCluskey, Gillean; Riddell, Sheila; Weedon, Elisabet; Fordyce, Mariela

    2016-01-01

    There has been an overall decrease in exclusion rates and numbers in recent years across the UK. This change has often been heralded as evidence that national inclusion policies are "working" and that schools themselves are becoming increasingly inclusive. This article examines findings from a recent study on school exclusion in Wales,…

  20. 36 CFR 907.10 - Categorical exclusion.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ENVIRONMENTAL QUALITY § 907.10 Categorical exclusion. The CEQ Regulations provide for the categorical exclusion... to this part, following public comment and review by the Council on Environmental Quality. ... human environment. Therefore, neither an environmental assessment nor an environmental impact statement...

  1. 36 CFR 907.10 - Categorical exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ENVIRONMENTAL QUALITY § 907.10 Categorical exclusion. The CEQ Regulations provide for the categorical exclusion... to this part, following public comment and review by the Council on Environmental Quality. ... human environment. Therefore, neither an environmental assessment nor an environmental impact statement...

  2. 49 CFR 236.911 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Exclusions. 236.911 Section 236.911 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... Train Control Systems § 236.911 Exclusions. (a) Does this subpart apply to existing systems? The...

  3. 49 CFR 236.911 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Exclusions. 236.911 Section 236.911 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... Train Control Systems § 236.911 Exclusions. (a) Does this subpart apply to existing systems? The...

  4. 49 CFR 236.911 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Exclusions. 236.911 Section 236.911 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... Train Control Systems § 236.911 Exclusions. (a) Does this subpart apply to existing systems? The...

  5. 49 CFR 236.911 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Exclusions. 236.911 Section 236.911 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... Train Control Systems § 236.911 Exclusions. (a) Does this subpart apply to existing systems? The...

  6. 49 CFR 236.911 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Exclusions. 236.911 Section 236.911 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... Train Control Systems § 236.911 Exclusions. (a) Does this subpart apply to existing systems? The...

  7. Women Combat Exclusion Policy: Relevant or Obsolete?

    DTIC Science & Technology

    2012-03-22

    to physically collocate and remain with direct ground combat units that are closed to women ; where units are engaged in long range reconnaissance... Women Combat Exclusion Policy: Relevant or Obsolete? by Lieutenant Colonel Melinda S. Romero United States Army...4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Women Combat Exclusion Policy: Relevant or Obsolete? 5b. GRANT NUMBER 5c

  8. 32 CFR 536.46 - Other exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Other exclusions. 536.46 Section 536.46 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.46 Other exclusions. (a) Statutory employer....

  9. 47 CFR 1.6005 - Exclusive defenses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Exclusive defenses. 1.6005 Section 1.6005... Against Satellite Carriers for Retransmission Without Consent § 1.6005 Exclusive defenses. (a) The defenses listed in paragraphs (a)(1) through (a)(4) of this section, are the only defenses available to a...

  10. 47 CFR 1.6005 - Exclusive defenses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Exclusive defenses. 1.6005 Section 1.6005... Against Satellite Carriers for Retransmission Without Consent § 1.6005 Exclusive defenses. (a) The defenses listed in paragraphs (a)(1) through (a)(4) of this section, are the only defenses available to a...

  11. 48 CFR 19.1504 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Exclusions. 19.1504 Section 19.1504 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Women-Owned Small Business (WOSB) Program 19.1504 Exclusions. This subpart...

  12. 48 CFR 19.1504 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false Exclusions. 19.1504 Section 19.1504 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Women-Owned Small Business (WOSB) Program 19.1504 Exclusions. This subpart...

  13. CMS results on exclusive and diffractive production

    SciTech Connect

    Alves, Gilvan A.

    2015-04-10

    We present recent CMS measurements of diffractive and exclusive processes, using data collected at 7 TeV at the LHC. Measurements of soft single- and double-diffractive cross sections are presented, as well as measurements of photon-induced processes including studies of exclusive WW production via photon-photon exchange.

  14. 40 CFR 68.126 - Exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Exclusion. 68.126 Section 68.126 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention § 68.126 Exclusion...

  15. 40 CFR 68.126 - Exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Exclusion. 68.126 Section 68.126 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention § 68.126 Exclusion...

  16. 40 CFR 68.126 - Exclusion.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Exclusion. 68.126 Section 68.126 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention § 68.126 Exclusion...

  17. 40 CFR 68.126 - Exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Exclusion. 68.126 Section 68.126 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention § 68.126 Exclusion...

  18. 40 CFR 68.126 - Exclusion.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Exclusion. 68.126 Section 68.126 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention § 68.126 Exclusion...

  19. 24 CFR 58.35 - Categorical exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Environmental Review Process: Documentation, Range of Activities, Project Aggregation and Classification § 58.35 Categorical exclusions. Categorical exclusion refers to a category of activities for which no environmental... needed with respect to environmental requirements, except where paragraph (c) of this section...

  20. Rescinding the Ground Combat Exclusion Policy

    DTIC Science & Technology

    2011-04-07

    Miller, " Feminism and the Exclusion of Army Women from Combat," in Women in the Military, ed. Rita James Simon (New Brunswick, NJ: Transaction...index.php/issuepapers (accessed November 23, 2010). Miller, Laura L. " Feminism and the Exclusion of Army Women from Combat." In Women in the Military

  1. 12 CFR 367.5 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... EXCLUSION OF CONTRACTOR AND TERMINATION OF CONTRACTS § 367.5 Exclusions. (a) The Ethics Counselor may... also prohibited from conducting business with FDIC as agents or representatives of other contractors... Ethics Counselor's decision to exclude the contractor pursuant to § 367.16. Provided further, that...

  2. Major depression in China-to-US immigrants and US-born Chinese Americans: testing a hypothesis from culture-gene co-evolutionary theory of mental disorders.

    PubMed

    Tan, Tony Xing

    2014-01-01

    In this study, the culture-gene co-evolutionary theory of mental disorders was used to test the hypothesis that major depression was less prevalent in China-to-US immigrants who migrated to the US as adults than in US-born adult Chinese Americans. Data from the Collaborative Psychiatric Epidemiology Surveys (CPES) were extracted for secondary data analyses on the rates of major depression disorder (MDD) and major depressive episode (MDE) in the two groups. Findings showed that for life time MDD, the rates for China-to-US immigrant and US-born Chinese were 5.3% and 7.9% for men and 8.5% and 33.1% for women. For 12-month MDD, the corresponding rates were 2.2% and 3.4% for men, and 4.7% and 12.6% for women. For life time MDE, the corresponding rates were 6.8% and 8.8% for men; for women the rates were 8.5% and 33.1%. For 12-month MDE, the rates were 2.2% and 4.4% for men; the rates were 4.7% and 12.6% for women. Controlling for age, education level, income, BMI, marital status, and income-to-needs ratio, China-to-US immigrant women remained less likely to have life time major depression than US-born Chinese American women. While the study has the strength of utilizing nationally representative datasets, the approach is limited as the data sources lack the capacity to investigate how the strength of connection with the collectivist culture might be related to major depression in the immigrant group. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Co-evolutionary Analysis of Domains in Interacting Proteins Reveals Insights into Domain–Domain Interactions Mediating Protein–Protein Interactions

    PubMed Central

    Jothi, Raja; Cherukuri, Praveen F.; Tasneem, Asba; Przytycka, Teresa M.

    2006-01-01

    Recent advances in functional genomics have helped generate large-scale high-throughput protein interaction data. Such networks, though extremely valuable towards molecular level understanding of cells, do not provide any direct information about the regions (domains) in the proteins that mediate the interaction. Here, we performed co-evolutionary analysis of domains in interacting proteins in order to understand the degree of co-evolution of interacting and non-interacting domains. Using a combination of sequence and structural analysis, we analyzed protein–protein interactions in F1-ATPase, Sec23p/Sec24p, DNA-directed RNA polymerase and nuclear pore complexes, and found that interacting domain pair(s) for a given interaction exhibits higher level of co-evolution than the noninteracting domain pairs. Motivated by this finding, we developed a computational method to test the generality of the observed trend, and to predict large-scale domain–domain interactions. Given a protein–protein interaction, the proposed method predicts the domain pair(s) that is most likely to mediate the protein interaction. We applied this method on the yeast interactome to predict domain–domain interactions, and used known domain–domain interactions found in PDB crystal structures to validate our predictions. Our results show that the prediction accuracy of the proposed method is statistically significant. Comparison of our prediction results with those from two other methods reveals that only a fraction of predictions are shared by all the three methods, indicating that the proposed method can detect known interactions missed by other methods. We believe that the proposed method can be used with other methods to help identify previously unrecognized domain–domain interactions on a genome scale, and could potentially help reduce the search space for identifying interaction sites. PMID:16949097

  4. Marketing energy services in a competitive environment

    SciTech Connect

    Mykytyn, R.B.

    1996-05-01

    For nearly six decades electrical utilities have operated in a regulated environment established by the Public Utilities Holding Company Act (PUHCA) of 1935. This legislation granted generators exclusive franchise to market electrical power in a given geographical area in return for the company`s commitment to provide safe, reliable and fairly-priced electrical power to all customers within the region. For close to 40 years, this system of regulated monopoly functioned reasonably well to maintain a balance among the varied, and at times competing, interests in the industry. During the 1970s, however, the public argument in favor of competition within the electrical services industry gained momentum. Spiraling energy costs focused the consumer`s attention on the need for conservation and inspired a variety of technological developments as well as experiments in cogeneration. Today, the electrical utility industry is poised for great change. Soon, this industry will follow the natural gas, telecommunications, and transportation industries into the uncharted waters of deregulation. The most pressing consequence of moving from a regulated environment to one that is deregulated - in other words, a competitive environment - is the need to design and implement a completely new form of marketing program. The response among industry marketing managers ranges from confusion and concern to excitement and eager anticipation. Where you fall along this continuum depends on how well you understand competitive marketing practices and the degree to which your company`s management group is willing to initiate competitive strategies and tactics now in preparation for the coming competitive marketplace.

  5. Exclusion and Education in South Africa: An Education Law Perspective of Emerging Alternative Understandings of Exclusion

    ERIC Educational Resources Information Center

    Beckmann, Johan

    2016-01-01

    The new democratic dispensation in South Africa (1994) was accompanied by law and policy aimed at preventing unfair exclusion from educational opportunities and promoting equal access to educational opportunities. However, feelings of unfair exclusion remain and new understandings of exclusion are emerging. This paper examines the new policy and…

  6. Maternal androgens in avian brood parasites and their hosts: responses to parasitism and competition?

    USGS Publications Warehouse

    Hahn, Caldwell; Wingfield, John C.; Fox, David M.; Walker, Brian G.; Thomley, Jill E

    2017-01-01

    In the coevolutionary dynamic of avian brood parasites and their hosts, maternal (or transgenerational) effects have rarely been investigated. We examined the potential role of elevated yolk testosterone in eggs of the principal brood parasite in North America, the brown-headed cowbird, and three of its frequent host species. Elevated maternal androgens in eggs are a common maternal effect observed in many avian species when breeding conditions are unfavorable. These steroids accelerate embryo development, shorten incubation period, increase nestling growth rate, and enhance begging vigor, all traits that can increase the survival of offspring. We hypothesized that elevated maternal androgens in host eggs are a defense against brood parasitism. Our second hypothesis was that elevated maternal androgens in cowbird eggs are a defense against intra-specific competition. For host species, we found that elevated yolk testosterone was correlated with parasitized nests of small species, those whose nest success is most reduced by cowbird parasitism. For cowbirds, we found that elevated yolk testosterone was correlated with eggs in multiply-parasitized nests, which indicate intra-specific competition for nests due to high cowbird density. We propose experimental work to further examine the use of maternal effects by cowbirds and their hosts.

  7. Dynamics of competitive systems with a single common limiting factor.

    PubMed

    Kon, Ryusuke

    2015-02-01

    The concept of limiting factors (or regulating factors) succeeded in formulating the well-known principle of competitive exclusion. This paper shows that the concept of limiting factors is helpful not only to formulate the competitive exclusion principle, but also to obtain other ecological insights. To this end, by focusing on a specific community structure, we study the dynamics of Kolmogorov equations and show that it is possible to derive an ecologically insightful result only from the information about interactions between species and limiting factors. Furthermore, we find that the derived result is a generalization of the preceding work by Shigesada, Kawasaki, and Teramoto (1984), who examined a certain Lotka-Volterra equation in a different context.

  8. Health plan competition in local markets.

    PubMed

    Grossman, J M

    2000-04-01

    To examine the structure of local health insurance markets and the strategies health plans were using to respond to competitive pressures in local markets in 1996/1997. Community Tracking Study site visits conducted between May 1996 and April 1997 in 12 U.S. markets selected to be nationally representative. In each site, 36 to 60 interviews on local health system change were conducted with healthcare industry informants representing health plans, providers, and purchasers. Relevant data for this article were abstracted from standardized protocols administered to multiple respondents in each site. Although the competitive threat from national plans was pervasive, local plans in most sites continued to retain strong, often dominant, positions in historically concentrated markets. In all sites, in response to purchaser pressures for stable premiums and provider choice, and the threat of entry and to plans were using three strategies to increase market share and market power: (1) consolidation/geographic expansion, (2) price competition, and (3) product line/segment diversification that focused on broad networks and open-access products. In most markets, in response to the demand for provider choice, the trend was away from ownership and exclusive arrangements with providers. Although local plans were moving to become full-service regional players, there was uncertainty about the abilities of all plans to sustain growth strategies at the expense of margins and organizational stability, and to effectively manage care with broad networks.

  9. Health plan competition in local markets.

    PubMed Central

    Grossman, J M

    2000-01-01

    OBJECTIVE: To examine the structure of local health insurance markets and the strategies health plans were using to respond to competitive pressures in local markets in 1996/1997. DATA SOURCES/STUDY SETTING: Community Tracking Study site visits conducted between May 1996 and April 1997 in 12 U.S. markets selected to be nationally representative. STUDY DESIGN: In each site, 36 to 60 interviews on local health system change were conducted with healthcare industry informants representing health plans, providers, and purchasers. DATA COLLECTION/EXTRACTION METHOD: Relevant data for this article were abstracted from standardized protocols administered to multiple respondents in each site. PRINCIPAL FINDINGS: Although the competitive threat from national plans was pervasive, local plans in most sites continued to retain strong, often dominant, positions in historically concentrated markets. In all sites, in response to purchaser pressures for stable premiums and provider choice, and the threat of entry and to plans were using three strategies to increase market share and market power: (1) consolidation/geographic expansion, (2) price competition, and (3) product line/segment diversification that focused on broad networks and open-access products. In most markets, in response to the demand for provider choice, the trend was away from ownership and exclusive arrangements with providers. CONCLUSIONS: Although local plans were moving to become full-service regional players, there was uncertainty about the abilities of all plans to sustain growth strategies at the expense of margins and organizational stability, and to effectively manage care with broad networks. PMID:10778822

  10. Competition-colonization dynamics

    PubMed Central

    Ojosnegros, Samuel; Beerenwinkel, Niko

    2010-01-01

    A single and purified clone of foot-and-mouth disease virus diversified in cell culture into two subpopulations that were genetically distinct. The subpopulation with higher virulence was a minority and was suppressed by the dominant but less virulent one. These two populations follow the competitioncolonization dynamics described in ecology. Virulent viruses can be regarded as colonizers because they killed the cells faster and they spread faster. The attenuated subpopulation resembles competitors because of its higher replication efficiency in coinfected cells. Our results suggest a new model for the evolution of virulence which is based on interactions between components of the quasispecies. Competition between viral mutants takes place at two levels, intracellular competition and competition for new cells. The two strategies are subjected to densitydependent selection. PMID:20798818

  11. IT product competition Network

    NASA Astrophysics Data System (ADS)

    Xu, Xiu-Lian; Zhou, Lei; Shi, Jian-Jun; Wang, Yong-Li; Feng, Ai-Xia; He, Da-Ren

    2008-03-01

    Along with the technical development, the IT product competition becomes increasingly fierce in recent years. The factories, which produce the same IT product, have to improve continuously their own product quality for taking a large piece of cake in the product sale market. We suggest using a complex network description for the IT product competition. In the network the factories are defined as nodes, and two nodes are connected by a link if they produce a common IT product. The edge represents the sale competition relationship. 2121 factories and 265 products have been investigated. Some statistical properties, such as the degree distribution, node strength distribution, assortativity, and node degree correlation have been empirically obtained.

  12. Price competition in procurement

    SciTech Connect

    Keisler, J.M.; Buehring, W.A.

    1996-07-01

    When creating a private market to provide a public good, government agencies can influence the market`s competitive characteristics. Markets have predictable, but often counterintuitive, behaviors. To succeed in applying available controls, and thereby reduce future costs, agencies must understand the behavior of the market. A model has been constructed to examine some issues in establishing competition for a structure in which there are economies of scale and government is obligated to purchase a fixed total quantity of a good. This model is used to demonstrate a way to estimate the cost savings from several alternative plans for a buyer exploring competitive procurement. The results are not and cannot be accurate for budgeting purposes; rather, they indicate the approximate magnitude of changes in cost that would be associated with changes in the market structure within which procurement occurs.

  13. Factors associated with latent fingerprint exclusion determinations.

    PubMed

    Ulery, Bradford T; Hicklin, R Austin; Roberts, Maria Antonia; Buscaglia, JoAnn

    2017-02-22

    Exclusion is the determination by a latent print examiner that two friction ridge impressions did not originate from the same source. The concept and terminology of exclusion vary among agencies. Much of the literature on latent print examination focuses on individualization, and much less attention has been paid to exclusion. This experimental study assesses the associations between a variety of factors and exclusion determinations. Although erroneous exclusions are more likely to occur on some images and for some examiners, they were widely distributed among images and examiners. Measurable factors found to be associated with exclusion rates include the quality of the latent, value determinations, analysis minutia count, comparison difficulty, and the presence of cores or deltas. An understanding of these associations will help explain the circumstances under which errors are more likely to occur and when determinations are less likely to be reproduced by other examiners; the results should also lead to improved effectiveness and efficiency of training and casework quality assurance. This research is intended to assist examiners in improving the examination process and provide information to the broader community regarding the accuracy, reliability, and implications of exclusion decisions.

  14. Advancing Manufacturing Research Through Competitions

    SciTech Connect

    Balakirsky, Stephen; Madhavan, Raj

    2009-01-01

    Competitions provide a technique for building interest and collaboration in targeted research areas. This paper will present a new competition that aims to increase collaboration amongst Universities, automation end-users, and automation manufacturers through a virtual competition. The virtual nature of the competition allows for reduced infrastructure requirements while maintaining realism in both the robotic equipment deployed and the scenarios. Details of the virtual environment as well as the competitions objectives, rules, and scoring metrics will be presented.

  15. Measuring hospital competition.

    PubMed

    White, S L; Chirikos, T N

    1988-03-01

    This paper appraises the use of the Herfindahl market share index as an exogenous competition variable in empirical studies of the hospital sector. An analysis of cross-sectional Florida data shows that this index itself is significantly influenced by the demand and supply factors commonly included in econometric models of hospital performance. The analysis then illustrates that biased inferences about the effects of market competition on the costs of hospital care may result unless the values of the Herfindahl Index are treated endogenously in hospital cost models.

  16. First Robotics Competition

    NASA Image and Video Library

    2010-03-05

    U.S. Senate Majority Leader Harry Reid, D-Nev., left, stands with Dean Kamen, the founder of First Robotics, as he talks about the importance of Science and Technology education during the First Robotics Competition, Friday March 5, 2010, in Washington. The student competition is called "For Inspiration and Recognition ofScience and Technology," or FIRST. The program was founded in 1989 by Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers)

  17. First Robotics Competition

    NASA Image and Video Library

    2010-03-05

    Students from the Highland School in Warrenton, Va. work on their robot in the "Pit Area" as they prepare to compete in the First Robotics Competition, Friday, March 5, 2010, in Washington. The student competition is called "For Inspiration and Recognition of Science and Technology," or FIRST. The program was founded in 1989 by inventor Dean Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers) Photo Credit: (NASA/Paul E. Alers)

  18. First Robotics Competition

    NASA Image and Video Library

    2010-03-05

    Students from McKinley Tech High School in Washington, D.C., work on their robot in the "Pit Area" as they prepare to compete in the First Robotics Competition, Friday, March 5, 2010, in Washington. The student competition is called "For Inspiration and Recognition of Science and Technology," or FIRST. The program was founded in 1989 by inventor Dean Kamen to inspire an appreciation of science and technology in young people, their schools and communities. Photo Credit: (NASA/Paul E. Alers)

  19. Aboveground insect herbivory increases plant competitive asymmetry, while belowground herbivory mitigates the effect.

    PubMed

    Borgström, Pernilla; Strengbom, Joachim; Viketoft, Maria; Bommarco, Riccardo

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenhouse experiment, we measured competition between two coexisting grass species that respond differently to nitrogen deposition: Dactylis glomerata L., which is competitively favoured by nitrogen addition, and Festuca rubra L., which is competitively favoured on nitrogen-poor soils. We predicted: (1) that aboveground herbivory would reduce competitive asymmetry at high soil nitrogen by reducing the competitive advantage of D. glomerata; and (2), that belowground herbivory would relax competition at low soil nitrogen, by reducing the competitive advantage of F. rubra. Aboveground herbivory caused a 46% decrease in the competitive ability of F. rubra, and a 23% increase in that of D. glomerata, thus increasing competitive asymmetry, independently of soil nitrogen level. Belowground herbivory did not affect competitive symmetry, but the combined influence of above- and belowground herbivory was weaker than predicted from their individual effects. Belowground herbivory thus mitigated the increased competitive asymmetry caused by aboveground herbivory. D. glomerata remained competitively dominant after the cessation of aboveground herbivory, showing that the influence of herbivory continued beyond the feeding period. We showed that insect herbivory can strongly influence plant competitive interactions. In our experimental plant community, aboveground insect herbivory increased the risk of competitive exclusion of F. rubra. Belowground herbivory appeared to mitigate the influence of

  20. Aboveground insect herbivory increases plant competitive asymmetry, while belowground herbivory mitigates the effect

    PubMed Central

    Strengbom, Joachim; Viketoft, Maria; Bommarco, Riccardo

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenhouse experiment, we measured competition between two coexisting grass species that respond differently to nitrogen deposition: Dactylis glomerata L., which is competitively favoured by nitrogen addition, and Festuca rubra L., which is competitively favoured on nitrogen-poor soils. We predicted: (1) that aboveground herbivory would reduce competitive asymmetry at high soil nitrogen by reducing the competitive advantage of D. glomerata; and (2), that belowground herbivory would relax competition at low soil nitrogen, by reducing the competitive advantage of F. rubra. Aboveground herbivory caused a 46% decrease in the competitive ability of F. rubra, and a 23% increase in that of D. glomerata, thus increasing competitive asymmetry, independently of soil nitrogen level. Belowground herbivory did not affect competitive symmetry, but the combined influence of above- and belowground herbivory was weaker than predicted from their individual effects. Belowground herbivory thus mitigated the increased competitive asymmetry caused by aboveground herbivory. D. glomerata remained competitively dominant after the cessation of aboveground herbivory, showing that the influence of herbivory continued beyond the feeding period. We showed that insect herbivory can strongly influence plant competitive interactions. In our experimental plant community, aboveground insect herbivory increased the risk of competitive exclusion of F. rubra. Belowground herbivory appeared to mitigate the influence of

  1. Hard Exclusive Vector Meson Leptoproduction At HERMES

    SciTech Connect

    Golembiovskaya, M.

    2011-07-15

    The HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson ({rho}{sup 0}{phi},{omega}) leptoproduction using the 27.6 GeV longitudinally polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas targets. Measurements of exclusive vector meson production provide access to the structure of the nucleon since the process can be described in terms of Generalized Parton Distributions (GPDs). An overview of the HERMES results on exclusive vector mesons production is presented.

  2. Market Exclusivity Time for Top Selling Originator Drugs in Canada: A Cohort Study.

    PubMed

    Lexchin, Joel

    2017-09-01

    This study looks at market exclusivity time for the top selling originator drugs in Canada. Total sales for drugs without competition were also calculated. A list of the top selling originator drugs by dollar sales from 2009 to 2015 inclusive, except for 2010, was compiled along with their annual sales. Health Canada databases were used to extract the following information: generic name, date of Notice of Compliance (NOC, date of marketing authorization), whether the product was a small molecule drug or a biologic, and date of NOC for a generic or biosimilar. Market exclusivity time was calculated in days for drugs. A total of 121 drugs were identified. There were 96 small molecule drugs (63 with a generic competitor and 33 with no generic competitor) and 25 biologics (none with a biosimilar competitor). The 63 drugs with a competitor had a mean market exclusivity time of 4478 days (12.3 years) (95% CI 4159-4798). The 58 drugs without competition had total annual sales of Can$8.59 billion and were on the market for a median of 5357 days (14.7 years) (interquartile range 3291-6679) as of January 31, 2017. Top selling originator drugs in Canada have a considerably longer period of market exclusivity than the 8 to 10 years that the research-based pharmaceutical industry claims. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  3. Determinants of Market Exclusivity for Prescription Drugs in the United States.

    PubMed

    Kesselheim, Aaron S; Sinha, Michael S; Avorn, Jerry

    2017-09-11

    The high prices of brand-name prescription drugs are a growing source of controversy in the United States. Manufacturers of brand-name drugs can command high prices because they are protected from generic competition by two types of government-granted monopoly rights. The first are patents on the drugs that generally define the basic period of brand-name-only sales. The second is awarded at the time of US Food and Drug Administration (FDA) approval and usually defines the minimum time until a generic can be sold. The initial patents last for 20 years and may be extended to account for time spent in clinical trials and regulatory review; other laws prevent approval of other manufacturers' versions of new drugs for about 6 to 7 years, and for new biologics for 12 years. Overall, most new drugs receive about 12 to 16 years of market exclusivity from both kinds of monopoly protection combined. We reviewed the peer-reviewed medical and health policy literature to identify studies that described the different types of patent protection and regulatory exclusivities that shield brand-name prescription drugs from competition and thus help to sustain high drug prices. We also identified potential policy reforms intended to modify exclusivity periods to address public health needs by balancing drug affordability and industry revenue. The goal of policy in this area should be to ensure that drug market exclusivity periods provide for fair return on investment but do not indefinitely block availability of lower-cost generic drugs.

  4. Competition and allelopathy with resource storage: two resources.

    PubMed

    Grover, James P; Wang, Feng-Bin

    2014-06-21

    Allelopathy is added to a familiar mathematical model of competition between two species for two essential resources in a chemostat environment. Both species store the resources, and each produces a toxin that induces mortality in the other species. The corresponding model without toxins displays outcomes of competitive exclusion independent of initial conditions, competitive exclusion that depends on initial conditions (bistability), and globally stable coexistence, depending on tradeoffs between competitors in growth requirements and consumption of the resources. Introducing toxins that act only between, and not within species, can destabilize coexistence leading to bistability or other multiple attractors. Invasibility of the missing species into a resident׳s semitrivial equilibrium is related to competitive outcomes. Mutual invasibility is necessary and sufficient for a globally stable coexistence equilibrium, but is not necessary for coexistence at a locally stable equilibrium. Invasibility of one semitrivial equilibrium but not the other is necessary but not sufficient for competitive exclusion independent of initial conditions. Mutual non-invasibility is necessary but not sufficient for bistability. Numerical analysis suggests that when competitors display bistability in the absence of toxin production, increases in the overall magnitude of resource supply cause bistability to arise over a larger range of supply ratios between the two resources. When competitors display coexistence in the absence of toxin production, increases in overall resource supply destabilize coexistence and produce bistability or other configurations of multiple attractors over large ranges of supply ratios. The emergence of multiple attractors at high resource supplies suggests that blooms of harmful algae producing allelopathic toxins could be difficult to predict under such rich conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Television and Competition.

    ERIC Educational Resources Information Center

    Noll, Roger G.

    The television industry is characterized by numerous imperfections in market competition. The spectrum allocation policy of the Federal Communications Commission (FCC) assures that there will be only three national television networks; consequently in nearly all markets these stations account for 75% to 100% of revenues. These networks in turn…

  6. Television and Competition.

    ERIC Educational Resources Information Center

    Noll, Roger G.

    The television industry is characterized by numerous imperfections in market competition. The spectrum allocation policy of the Federal Communications Commission (FCC) assures that there will be only three national television networks; consequently in nearly all markets these stations account for 75% to 100% of revenues. These networks in turn…

  7. Competitiveness and Campaign '88.

    ERIC Educational Resources Information Center

    Kernan-Schloss, Adam, Ed.; And Others

    This report profiles the positions of the six Democratic and six Republican 1988 presidential candidates on policy issues affecting U.S. competitiveness in the global economy. Candidate profiles are provided for: Bruce Babbitt, Michael Dukakis, Richard Gephardt, Albert Gore, Jr., Jesse Jackson, and Paul Simon (Democrats); and George Bush, Robert…

  8. Building Camaraderie from Competition

    ERIC Educational Resources Information Center

    Marino, Gordon

    2007-01-01

    Educational institutions have adopted athletics programs to promote character building. Sports help people feel comfortable in their skins and provide unique opportunities to develop qualities such as cooperation, perseverance, and the ability to cope with fear. But the arena can be a hothouse for more primal feelings that emerge in competition.…

  9. Growing Competition for Libraries.

    ERIC Educational Resources Information Center

    Gibbons, Susan

    2001-01-01

    Describes the Questia subscription-based online academic digital books library. Highlights include weaknesses of the collection; what college students want from a library; importance of marketing; competition for traditional academic libraries that may help improve library services; and the ability of Questia to overcome barriers and…

  10. Growing Competition for Libraries.

    ERIC Educational Resources Information Center

    Gibbons, Susan

    2001-01-01

    Describes the Questia subscription-based online academic digital books library. Highlights include weaknesses of the collection; what college students want from a library; importance of marketing; competition for traditional academic libraries that may help improve library services; and the ability of Questia to overcome barriers and…

  11. Reed Hundt's Friendly Competition.

    ERIC Educational Resources Information Center

    Educom Review, 1996

    1996-01-01

    Presents an interview with Reed Hundt, Chairman of the Federal Communications Commission (FCC), who implemented the Education Task Force to coordinate the FCC's role in educational provisions of the Telecommunications Act of 1996. He asserts that writing clear rules for the communications sector will promote competition and ensure educational…

  12. Competition in the Classroom

    ERIC Educational Resources Information Center

    Jameson, Daphne

    2007-01-01

    In this article, the author shares the strategy she adopted to even out the participation among her multicultural students during their classroom discussions. The author realized that her students had different concepts about the classroom and different philosophies about competition. For the Americans and Indians, the classroom was a site of…

  13. Competitiveness Index 1990.

    ERIC Educational Resources Information Center

    Council on Competitiveness, Washington, DC.

    The United States' economic performance in the world economy is compared with that of Canada, France, Germany, Italy, Japan, and the United Kingdom (the Summit 7 countries). Competitiveness is assessed by four economic indicators: standard of living, trade, manufacturing productivity, and investment. The United States continues to outinvest the…

  14. Competitiveness Index 1990.

    ERIC Educational Resources Information Center

    Council on Competitiveness, Washington, DC.

    The United States' economic performance in the world economy is compared with that of Canada, France, Germany, Italy, Japan, and the United Kingdom (the Summit 7 countries). Competitiveness is assessed by four economic indicators: standard of living, trade, manufacturing productivity, and investment. The United States continues to outinvest the…

  15. Competition in Advertising.

    ERIC Educational Resources Information Center

    Avery, Jim

    1991-01-01

    Discusses five ways (high school newspaper and yearbook advertising, summer jobs, internships, contests, and student-run advertising agencies) students can start to prepare for a career in the competitive field of advertising while still in high school and college. (SR)

  16. A Winning Competition

    ERIC Educational Resources Information Center

    Geddes, Kim; Franchini, Elease

    2012-01-01

    As a high school physics teacher, Kim Geddes is constantly searching for new experiences to challenge, motivate, and engage students. Last year, she incorporated ExploraVision into the energy unit of her school's physics curriculum with the help of their media specialist (Elease Franchini). ExploraVision is a competition offered through a…

  17. Competition in Individualized CAI.

    ERIC Educational Resources Information Center

    Hativa, Nira; And Others

    1993-01-01

    Examines the effects of competition and cooperation on learning through computer-assisted instruction (CAI). A questionnaire was administered to 457 Israeli fourth graders who used two CAI arithmetic systems. The characteristics of the systems are discussed, and the results of the survey are correlated to students' gender and achievement levels.…

  18. Building Camaraderie from Competition

    ERIC Educational Resources Information Center

    Marino, Gordon

    2007-01-01

    Educational institutions have adopted athletics programs to promote character building. Sports help people feel comfortable in their skins and provide unique opportunities to develop qualities such as cooperation, perseverance, and the ability to cope with fear. But the arena can be a hothouse for more primal feelings that emerge in competition.…

  19. Positioning for Competition.

    ERIC Educational Resources Information Center

    Lapovsky, Lucie; Hubbell, Loren Loomis

    2000-01-01

    Analyzes results of the 1999 National Association of College and Business Officers tuition discounting survey and identifies trends. Finds colleges and universities are reactively responding to market pressures and proactively trying to analyze and position themselves ahead of the competition, often regional rather than national, for the…

  20. Human Resources Competitiveness Profile.

    ERIC Educational Resources Information Center

    Council on Competitiveness, Washington, DC.

    This report distills hundreds of indicators from both domestic and international sources to determine how the United States compares to other countries and to its own past performance in competitiveness. It attempts to establish a baseline of some key education and training indicators that, taken together, show where the nation stands and where it…

  1. A Winning Competition

    ERIC Educational Resources Information Center

    Geddes, Kim; Franchini, Elease

    2012-01-01

    As a high school physics teacher, Kim Geddes is constantly searching for new experiences to challenge, motivate, and engage students. Last year, she incorporated ExploraVision into the energy unit of her school's physics curriculum with the help of their media specialist (Elease Franchini). ExploraVision is a competition offered through a…

  2. Competition in the Classroom

    ERIC Educational Resources Information Center

    Jameson, Daphne

    2007-01-01

    In this article, the author shares the strategy she adopted to even out the participation among her multicultural students during their classroom discussions. The author realized that her students had different concepts about the classroom and different philosophies about competition. For the Americans and Indians, the classroom was a site of…

  3. 48 CFR 37.202 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CONTRACTING SERVICE CONTRACTING Advisory and Assistance Services 37.202 Exclusions. The following activities...) Routine information technology services unless they are an integral part of a contract for the acquisition... research involving medical, biological, physical, social, psychological, or other phenomena....

  4. 48 CFR 37.502 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 37.502 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING SERVICE CONTRACTING Management Oversight of Service Contracts 37.502 Exclusions. (a) This subpart... subpart. However, good management practices and contract administration techniques should be used...

  5. 48 CFR 19.1504 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PROGRAMS SMALL BUSINESS PROGRAMS Women-Owned Small Business (WOSB) Program 19.1504 Exclusions. This subpart... award to— (1) Federal Prison Industries, Inc. (see subpart 8.6); or (2) Javits-Wagner-O'Day Act...

  6. 48 CFR 19.1504 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... PROGRAMS SMALL BUSINESS PROGRAMS Women-Owned Small Business (WOSB) Program 19.1504 Exclusions. This subpart... award to— (1) Federal Prison Industries, Inc. (see subpart 8.6); or (2) Javits-Wagner-O'Day Act...

  7. Teaching With Documents: Chinese Exclusion Forms.

    ERIC Educational Resources Information Center

    Simmons, Linda, Ed.

    1986-01-01

    Reviews the history of Chinese immigration to the United States and provides a facsimilie of a form used to document immigrants under the Chinese Exclusion Act. Teaching suggestions are included. (JDH)

  8. Exclusion of pneumothorax by radionuclide lung scan

    SciTech Connect

    Weiss, P.E.

    1986-05-01

    A case is reported in which ventilation lung imaging was useful in excluding a large pneumothorax. This technique may be helpful in patients with emphysema in whom exclusion of pneumothorax by radiographic criteria might be difficult.

  9. Central exclusive production and the Durham model

    NASA Astrophysics Data System (ADS)

    Harland-Lang, L. A.; Khoze, V. A.; Ryskin, M. G.

    2014-11-01

    We review some selected results within the Durham model of central exclusive production. We discuss the theoretical aspects of this approach and consider the phenomenological implications for a selection of processes.

  10. 40 CFR 113.5 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SMALL ONSHORE STORAGE FACILITIES Oil Storage Facilities § 113.5 Exclusions. This subpart does not apply to: (a) Those facilities whose average daily oil throughout is more than their fixed oil...

  11. 40 CFR 113.5 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SMALL ONSHORE STORAGE FACILITIES Oil Storage Facilities § 113.5 Exclusions. This subpart does not apply to: (a) Those facilities whose average daily oil throughout is more than their fixed oil...

  12. 40 CFR 113.5 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SMALL ONSHORE STORAGE FACILITIES Oil Storage Facilities § 113.5 Exclusions. This subpart does not apply to: (a) Those facilities whose average daily oil throughout is more than their fixed oil...

  13. 40 CFR 113.5 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SMALL ONSHORE STORAGE FACILITIES Oil Storage Facilities § 113.5 Exclusions. This subpart does not apply to: (a) Those facilities whose average daily oil throughout is more than their fixed oil...

  14. 40 CFR 113.5 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SMALL ONSHORE STORAGE FACILITIES Oil Storage Facilities § 113.5 Exclusions. This subpart does not apply to: (a) Those facilities whose average daily oil throughout is more than their fixed oil...

  15. 32 CFR 989.13 - Categorical exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ENVIRONMENTAL IMPACT ANALYSIS PROCESS (EIAP) § 989.13 Categorical exclusion. (a) CATEXs define those categories... environment and do not, therefore, require further environmental analysis in an EA or an EIS. The list of...

  16. 42 CFR 1001.1901 - Scope and effect of exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Scope and effect of exclusion. 1001.1901 Section... SERVICES OIG AUTHORITIES PROGRAM INTEGRITY-MEDICARE AND STATE HEALTH CARE PROGRAMS Waivers and Effect of Exclusion § 1001.1901 Scope and effect of exclusion. (a) Scope of exclusion. Exclusions of individuals...

  17. The Cost Effectiveness of LAA Exclusion.

    PubMed

    Kreidieh, Bahij; Mañero, Moisés Rodríguez; Cortez, Sergio H Ibarra; Schurmann, Paul; Valderrábano, Miguel

    2016-01-01

    Left atrial appendage (LAA) exclusion strategies are increasingly utilized for stroke prevention in lieu of oral anticoagulants. Reductions in bleeding risk and long-term compliance issues bundled with comparable stroke prevention benefits have made these interventions increasingly attractive. Unfortunately, healthcare funding remains limited. Comparative cost economic analyses are therefore critical in optimizing resource allocation. In this review we seek to discourse the cost economics analysis of LAA exclusion over available therapeutic alternatives (warfarin and the new oral anticoagulants (NOACs)). .

  18. History of the Combat Zone Tax Exclusion

    DTIC Science & Technology

    2011-09-01

    married members) exemption that precisely offset a contemporaneous cut in the personal deduction. Unlike its WWI predecessor, the 1942 exclusion was not...tax benefits with regard to Cold War conflicts. In the Korean War, these goals were achieved with a timely extension and termination of the combat...captured, or missing in Cambodia , though eligible for income tax exclusions by virtue of their formal deployment location, were ineligible for v

  19. Exclusive Reactions Involving Pions and Nucleons

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Blattnig, Steve R.; Tripathi, R. K.

    2002-01-01

    The HZETRN code requires inclusive cross sections as input. One of the methods used to calculate these cross sections requires knowledge of all exclusive processes contributing to the inclusive reaction. Conservation laws are used to determine all possible exclusive reactions involving strong interactions between pions and nucleons. Inclusive particle masses are subsequently determined and are needed in cross-section calculations for inclusive pion production.

  20. Model of reversible vesicular transport with exclusion

    NASA Astrophysics Data System (ADS)

    Bressloff, Paul C.; Karamched, Bhargav R.

    2016-08-01

    A major question in neurobiology concerns the mechanics behind the motor-driven transport and delivery of vesicles to synaptic targets along the axon of a neuron. Experimental evidence suggests that the distribution of vesicles along the axon is relatively uniform and that vesicular delivery to synapses is reversible. A recent modeling study has made explicit the crucial role that reversibility in vesicular delivery to synapses plays in achieving uniformity in vesicle distribution, so called synaptic democracy (Bressloff et al 2015 Phys. Rev. Lett. 114 168101). In this paper we generalize the previous model by accounting for exclusion effects (hard-core repulsion) that may occur between molecular motor-cargo complexes (particles) moving along the same microtubule track. The resulting model takes the form of an exclusion process with four internal states, which distinguish between motile and stationary particles, and whether or not a particle is carrying vesicles. By applying a mean field approximation and an adiabatic approximation we reduce the system of ODEs describing the evolution of occupation numbers of the sites on a 1D lattice to a system of hydrodynamic equations in the continuum limit. We find that reversibility in vesicular delivery allows for synaptic democracy even in the presence of exclusion effects, although exclusion does exacerbate nonuniform distributions of vesicles in an axon when compared with a model without exclusion. We also uncover the relationship between our model and other models of exclusion processes with internal states.

  1. Socio-technical transition as a co-evolutionary process: Innovation and the role of niche markets in the transition to motor vehicles

    NASA Astrophysics Data System (ADS)

    Birky, Alicia K.

    2008-10-01

    Significant reductions in greenhouse emissions from personal transportation will require a transition to an alternative technology regime based on renewable energy sources. Two bodies of research, the quasi-evolutionary (QE) model and the multi-level perspective (MLP) assert that processes within niches play a fundamental role in such transitions. This research asks whether the description of transitions based on this niche hypothesis and its underlying assumptions is consistent with the historical U.S. transition to motor vehicles at the beginning of the 20th century. Unique to this dissertation is the combination of the perspective of the entrepreneur with co-evolutionary approaches to socio-technical transitions. This approach is augmented with concepts from the industry life-cycle model and with a taxonomy of mechanisms of learning. Using this analytic framework, I examine specifically the role of entrepreneurial behavior and processes within and among firms in the co-evolution of technologies and institutions during the transition to motor vehicles. I find that niche markets played an important role in the development of the technology, institutions, and the industry. However, I also find that the diffusion of the automobile is not consistent with the niche hypothesis in the following ways: (1) product improvements and cost reductions were not realized in niche markets, but were achieved simultaneously with diffusion into mass markets; (2) in addition to learning-by-doing and learning-by-interacting with users, knowledge spillovers and interacting with suppliers were critical in this process; (3) cost reductions were not automatic results of expanding markets, but rather arose from the strategies of entrepreneurs based on personal perspectives and values. This finding supports the use of a behavioral approach with a micro-focus in the analysis of socio-technical change. I also find that the emergence and diffusion of the motor vehicle can only be understood by

  2. Environmental structure and competitive scoring advantages in team competitions.

    PubMed

    Merritt, Sears; Clauset, Aaron

    2013-10-29

    In most professional sports, playing field structure is kept neutral so that scoring imbalances may be attributed to differences in team skill. It thus remains unknown what impact environmental heterogeneities can have on scoring dynamics or competitive advantages. Applying a novel generative model of scoring dynamics to roughly 10 million team competitions drawn from an online game, we quantify the relationship between the structure within a competition and its scoring dynamics, while controlling the impact of chance. Despite wide structural variations, we observe a common three-phase pattern in the tempo of events. Tempo and balance are highly predictable from a competition's structural features alone and teams exploit environmental heterogeneities for sustained competitive advantage. Surprisingly, the most balanced competitions are associated with specific environmental heterogeneities, not from equally skilled teams. These results shed new light on the design principles of balanced competition, and illustrate the potential of online game data for investigating social dynamics and competition.

  3. Environmental structure and competitive scoring advantages in team competitions

    NASA Astrophysics Data System (ADS)

    Merritt, Sears; Clauset, Aaron

    2013-10-01

    In most professional sports, playing field structure is kept neutral so that scoring imbalances may be attributed to differences in team skill. It thus remains unknown what impact environmental heterogeneities can have on scoring dynamics or competitive advantages. Applying a novel generative model of scoring dynamics to roughly 10 million team competitions drawn from an online game, we quantify the relationship between the structure within a competition and its scoring dynamics, while controlling the impact of chance. Despite wide structural variations, we observe a common three-phase pattern in the tempo of events. Tempo and balance are highly predictable from a competition's structural features alone and teams exploit environmental heterogeneities for sustained competitive advantage. Surprisingly, the most balanced competitions are associated with specific environmental heterogeneities, not from equally skilled teams. These results shed new light on the design principles of balanced competition, and illustrate the potential of online game data for investigating social dynamics and competition.

  4. Asymmetric competition between distant taxa: poecilid fishes and water striders.

    PubMed

    Englund, Göran; Johansson, Frank; Olsson, Tommy I

    1992-12-01

    Competition for water surface prey between fish (Priapichtus annectens: Poeciliidae) and water striders (Potamobates unidentatus: Gerridae) was studied in the laboratory and in pools in a small tropical stream. Laboratory experiments showed that fish depressed activity and foraging success of water striders. Large fish (4-5 cm) had a greater effect than small fish (2-3 cm). The field experiment showed that competition was highly asymmetric. Presence of fish decreased water strider foraging success while the reverse interaction was insignificant. It is suggested that the higher individual foraging success of the fish, harassment of water striders by fish and the use of an exclusive resource, benthic invertebrates, by the fish, contribute to this pattern. Habitat use differed between the two species. Fish used the deeper parts of stream pools and water striders used the shallower parts of the pools. Asymmetric interference and exploitation competition may force water striders to use shallow edge habitats.

  5. Competitive exclusion: an ecological model demonstrates how research metrics can drive women out of science

    NASA Astrophysics Data System (ADS)

    O'Brien, K.; Hapgood, K.

    2012-12-01

    While universities are often perceived within the wider population as a flexible family-friendly work environment, continuous full-time employment remains the norm in tenure track roles. This traditional career path is strongly re-inforced by research metrics, which typically measure accumulated historical performance. There is a strong feedback between historical and future research output, and there is a minimum threshold of research output below which it becomes very difficult to attract funding, high quality students and collaborators. The competing timescales of female fertility and establishment of a research career mean that many women do not exceed this threshold before having children. Using a mathematical model taken from an ecological analogy, we demonstrate how these mechanisms create substantial barriers to pursuing a research career while working part-time or returning from extended parental leave. The model highlights a conundrum for research managers: metrics can promote research productivity and excellence within an organisation, but can classify highly capable scientists as poor performers simply because they have not followed the traditional career path of continuous full-time employment. Based on this analysis, we make concrete recommendations for researchers and managers seeking to retain the skills and training invested in female scientists. We also provide survival tactics for women and men who wish to pursue a career in science while also spending substantial time and energy raising their family.

  6. ABSENCE OF AEDES AEGYPTI (L.) ON AN ECOLOGICAL ISLAND: COMPETITIVE EXCLUSION?

    PubMed

    Afizah, A Noor; Mahirah, M N; Azahari, A H; Asuad, M Khairul; Nazni, W A; Lee, H L

    2015-09-01

    Ovitrap surveillance was conducted in 2012 and 2006 in Malay and Aboriginal Villages on Carey Island. In each village, standard ovitraps were placed indoors and outdoors at randomly selected houses/locations. All L3 larvae recovered were identified up to species level. Results demonstrated that only larvae of Aedes albopictus were found in all the positive ovitraps placed indoors and outdoors. In 2012, a high ovitrap index (OI) of 66.7% indoor and 84.0% outdoor in the Malay Village; and 62.5% indoor and 88.0% outdoor in Aboriginal Village with an apparent absence of Aedes aegypti. In 2006, a 100% OI was recorded in all ovitraps set indoors and outdoors in both villages.

  7. Demolishing the competition: the longitudinal link between competitive video games, competitive gambling, and aggression.

    PubMed

    Adachi, Paul J C; Willoughby, Teena

    2013-07-01

    The majority of research on the link between video games and aggression has focused on the violent content in games. In contrast, recent experimental research suggests that it is video game competition, not violence, that has the greatest effect on aggression in the short-term. However, no researchers have examined the long-term relationship between video game competition and aggression. In addition, if competition in video games is a significant reason for the link between video game play and aggression, then other competitive activities, such as competitive gambling, also may predict aggression over time. In the current study, we directly assessed the socialization (competitive video game play and competitive gambling predicts aggression over time) versus selection hypotheses (aggression predicts competitive video game play and competitive gambling over time). Adolescents (N = 1,492, 50.8 % female) were surveyed annually from Grade 9 to Grade 12 about their video game play, gambling, and aggressive behaviors. Greater competitive video game play and competitive gambling predicted higher levels of aggression over time, after controlling for previous levels of aggression, supporting the socialization hypothesis. The selection hypothesis also was supported, as aggression predicted greater competitive video game play and competitive gambling over time, after controlling for previous competitive video game play and competitive gambling. Our findings, taken together with the fact that millions of adolescents play competitive video games every day and that competitive gambling may increase as adolescents transition into adulthood, highlight the need for a greater understanding of the relationship between competition and aggression.

  8. Details on Exclusive Use Data Protection for Minor Use Registrations

    EPA Pesticide Factsheets

    This document provides information about issues related to exclusive use data protection for minor use registrations, including extension of the exclusive use period and establishing a new exclusive use period.

  9. 5 CFR 919.1020 - Voluntary exclusion or voluntarily excluded.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) CIVIL SERVICE REGULATIONS (CONTINUED) GOVERNMENTWIDE DEBARMENT AND SUSPENSION (NONPROCUREMENT) Definitions § 919.1020 Voluntary exclusion or voluntarily excluded. (a) Voluntary exclusion means a person's.... Voluntary exclusion must have governmentwide effect. (b) Voluntarily excluded means the status of a...

  10. Teenage pregnancy and exclusive breastfeeding rates.

    PubMed

    Puapompong, Pawin; Raungrongmorakot, Kasem; Manolerdtewan, Wichian; Ketsuwan, Sukwadee; Wongin, Sinutchanan

    2014-09-01

    Teenage pregnancy is an important health issue globally and in Thailand Younger age mothers decide on the breastfeeding practices ofthe first 6-month. To find the rates of 6-month exclusive breastfeeding practices of teenage mothers and compare them with the rates of 6-month exclusive breastfeeding practices in mothers who are 20 years of age or more. Three thousand five hundred sixty three normal, postpartum women, who delivered without complications at the HRH Princess Maha Chakri Sirindhorn Medical Center in the Nakhon Nayok Province between 2010 and2013 were included in this study. At the second daypostpartum, the data of latch scores and the data of the practice of exclusive breastfeeding were collected Telephone follow-ups on the seventh, fourteenth, and forty-fifth postpartum days and at the second, fourth, and sixth month postpartum month were collected and used for exclusive breastfeeding data following discharge. Demographic data included the maternal age, parity, gestational age, marital status, occupation, religion, route ofdelivery, estimated blood loss, body mass index, nipple length, and the childs birth weight. The collected data was analyzed by the t-test, Chi-square, and odds ratio with 95% confidence interval. The percentage of teenage pregnancies was at 14.8% (527 cases). On postpartum day 2, the percentage of latch scores of 8 or less was 66.4%. At the seventh, fourteenth, and forty-fifth day and at the second, fourth, and sixth months postpartum, the exclusive breastfeeding rates were 88.5, 78.5, 57.6, 43.1, 32.9, and27.0%, respectively. Comparison of the 6-month exclusive breastfeeding rates between teenage mothers and mothers 20 years ofage or older were not statistically significant (p<0.05). The 6-month exclusive breastfeeding rate of teenage mothers was at 27.0% and had no significant differences from the rates of mothers 20 years of age or more.

  11. Improved self-exclusion program: preliminary results.

    PubMed

    Tremblay, Nicole; Boutin, Claude; Ladouceur, Robert

    2008-12-01

    The gambling industry has offered self-exclusion programs for quite a long time. Such measures are designed to limit access to gaming opportunities and provide problem gamblers with the help they need to cease or limit their gambling behaviour. However, few studies have empirically evaluated these programs. This study has three objectives: (1) to observe the participation in an improved self-exclusion program that includes an initial voluntary evaluation, phone support, and a mandatory meeting, (2) to evaluate satisfaction and usefulness of this service as perceived by self-excluders, (3) to measure the preliminary impact of this improved program. One hundred sixteen self-excluders completed a questionnaire about their satisfaction and their perception of the usefulness during the mandatory meeting. Among those participants, 39 attended an initial meeting. Comparisons between data collected at the initial meeting and data taken at the final meeting were made for those 39 participants. Data showed that gamblers chose the improved self-exclusion program 75% of the time; 25% preferred to sign a regular self-exclusion contract. Among those who chose the improved service, 40% wanted an initial voluntary evaluation and 37% of these individuals actually attended that meeting. Seventy percent of gamblers came to the mandatory meeting, which was a required condition to end their self-exclusion. The majority of participants were satisfied with the improved self-exclusion service and perceived it as useful. Major improvements were observed between the final and the initial evaluation on time and money spent, consequences of gambling, DSM-IV score, and psychological distress. The applicability of an improved self-exclusion program is discussed and, as shown in our study, the inclusion of a final mandatory meeting might not be so repulsive for self-excluders. Future research directives are also proposed.

  12. Gene-Culture Coevolutionary Games

    ERIC Educational Resources Information Center

    Blute, Marion

    2006-01-01

    Gene-culture interactions have largely been modelled employing population genetic-type models. Moreover, in the most notable application to date, the "interactive" modes have been one way rather than bidirectional. This paper suggests using game theoretic, fully interactive models. Employing the logic utilized in population ecology for coevolution…

  13. Gene-Culture Coevolutionary Games

    ERIC Educational Resources Information Center

    Blute, Marion

    2006-01-01

    Gene-culture interactions have largely been modelled employing population genetic-type models. Moreover, in the most notable application to date, the "interactive" modes have been one way rather than bidirectional. This paper suggests using game theoretic, fully interactive models. Employing the logic utilized in population ecology for coevolution…

  14. Autonomic and Coevolutionary Sensor Networking

    NASA Astrophysics Data System (ADS)

    Boonma, Pruet; Suzuki, Junichi

    (WSNs) applications are often required to balance the tradeoffs among conflicting operational objectives (e.g., latency and power consumption) and operate at an optimal tradeoff. This chapter proposes and evaluates a architecture, called BiSNET/e, which allows WSN applications to overcome this issue. BiSNET/e is designed to support three major types of WSN applications: , and hybrid applications. Each application is implemented as a decentralized group of, which is analogous to a bee colony (application) consisting of bees (agents). Agents collect sensor data or detect an event (a significant change in sensor reading) on individual nodes, and carry sensor data to base stations. They perform these data collection and event detection functionalities by sensing their surrounding network conditions and adaptively invoking behaviors such as pheromone emission, reproduction, migration, swarming and death. Each agent has its own behavior policy, as a set of genes, which defines how to invoke its behaviors. BiSNET/e allows agents to evolve their behavior policies (genes) across generations and autonomously adapt their performance to given objectives. Simulation results demonstrate that, in all three types of applications, agents evolve to find optimal tradeoffs among conflicting objectives and adapt to dynamic network conditions such as traffic fluctuations and node failures/additions. Simulation results also illustrate that, in hybrid applications, data collection agents and event detection agents coevolve to augment their adaptability and performance.

  15. The Literature of Competitive Intelligence.

    ERIC Educational Resources Information Center

    Walker, Thomas D.

    1994-01-01

    Describes competitive intelligence (CI) literature in terms of its location, quantity, authorship, length, and problems of bibliographic access. Highlights include subject access; competitive intelligence research; espionage and security; monographs; and journals. (21 references) (LRW)

  16. The Literature of Competitive Intelligence.

    ERIC Educational Resources Information Center

    Walker, Thomas D.

    1994-01-01

    Describes competitive intelligence (CI) literature in terms of its location, quantity, authorship, length, and problems of bibliographic access. Highlights include subject access; competitive intelligence research; espionage and security; monographs; and journals. (21 references) (LRW)

  17. The evolution of increased competitive ability, innate competitive advantages, and novel biochemical weapons act in concert for a tropical invader.

    PubMed

    Qin, Rui-Min; Zheng, Yu-Long; Valiente-Banuet, Alfonso; Callaway, Ragan M; Barclay, Gregor F; Pereyra, Carlos Silva; Feng, Yu-Long

    2013-02-01

    There are many non-mutually exclusive mechanisms for exotic invasions but few studies have concurrently tested more than one hypothesis for the same species. Here, we tested the evolution of increased competitive ability (EICA) hypothesis in two common garden experiments in which Chromolaena odorata plants originating from native and nonnative ranges were grown in competition with natives from each range, and the novel weapons hypothesis in laboratory experiments with leachates from C. odorata. Compared with conspecifics originating from the native range, C. odorata plants from the nonnative range were stronger competitors at high nutrient concentrations in the nonnative range in China and experienced far more herbivore damage in the native range in Mexico. In both China and Mexico, C. odorata was more suppressed by species native to Mexico than by species native to China. Species native to China were much more inhibited by leaf extracts from C. odorata than species from Mexico, and this difference in allelopathic effects may provide a possible explanation for the biogeographic differences in competitive ability. Our results indicate that EICA, innate competitive advantages, and novel biochemical weapons may act in concert to promote invasion by C. odorata, and emphasize the importance of exploring multiple, non-mutually exclusive mechanisms for invasions.

  18. Welfare of competition horses.

    PubMed

    Atock, M A; Williams, R B

    1994-03-01

    In the large majority of cases and circumstances, horses benefit from their association with man. However, abuse of horses can occur, due to neglect or through the pressures of competition. The welfare of all animals, including competition horses, has become increasingly topical over the past ten years. Equestrian sport is coming under closer public scrutiny due to reports of apparent abuse. The bodies responsible for regulating these sports strenuously endeavour to protect the welfare of horses which compete under their rules and regulations. The Fédération Equestre Internationale (FEI: International Equestrian Federation) is the sole authority for all international events in dressage, show-jumping, three-day event, driving, endurance riding and vaulting. The FEI rules illustrate the ways in which the welfare of competing horses is safeguarded.

  19. Designing Competitive Service Models

    NASA Astrophysics Data System (ADS)

    Martinez, Veronica; Turner, Trevor

    The explosives developed in Europe in the late nineteenth and early twentieth ­century by the famous Swede and patron of the world peace prize, Alfred Nobel, were extremely durable and, apart from the introduction of the electric detonator, have remained in use with minor modifications for almost a century (Fig. 5.1a). In the 1970s a new invention started a process of change that has transformed the explosives business from being a supplier of products to a provider of a service. Survival very much depended on the agility of ICI Explosives UK, hereinafter referred to as "ICI Explosives," in adapting to the new competitive environment. Manufacturing excellence was not a solution. Innovative thinking was required to sustain the ­business as changes in technology reduced the complexity that had ­protected the business from serious competition for over a century.

  20. Managed competition that works.

    PubMed

    Caper, P

    1993-05-19

    President Clinton has advocated managed competition within a global budget as a long-term strategy for simultaneously controlling health care costs and expanding access to medical care to all Americans. This proposal is intended to show how these two seemingly conflicting goals can be simultaneously accomplished. Managed competition, as it has been conceptualized to date, is primarily a strategy for reforming the system of providing health services. To work, it must be joined with a strategy for reforming our system of financing and paying for those services and of limiting overall system capacity. "Managed Competition That Works" is a proposal that would create a single trust-funded national system of health insurance, implemented through a system of vouchers to individuals. Global budgeting would be accomplished through establishment of the voucher's value each year. The trust fund would pay health plans for all medical care by capitation, but health plans would be free to negotiate a variety of payment arrangements with physicians, hospitals, and other providers. All plans would be required to offer a standard package of benefits, but would have great flexibility in offering benefits beyond the scope of the standard package, if those benefits replace high-cost with lower-cost services or permit the plan to compete more effectively for market share. This proposal would establish firm but acceptable national budget limits; provide universal, comprehensive, and uniform insurance coverage; eliminate cost shifting; encourage competition; reward efficiency-improving innovation; greatly reduce the need for centralized micromanagement of medical care; and retain local determination and a somewhat reduced level of consumer choice. Although this proposal is written as a national plan, trust funds could be implemented at the state level, if problems associated with portability of benefits among states could be solved.

  1. Staphylococci in Competition1

    PubMed Central

    Peterson, A. C.; Black, J. J.; Gunderson, M. F.

    1964-01-01

    Previous results showed definite repressive effects on the growth of staphylococci in mixed cultures due to the competitive growth of psychrophilic saprophytes. This study was continued, and the influence of other environmental factors, pH and salt, on the competition between staphylococci and saprophytes was investigated. Initial pH values varied from 5 to 9. At the extremes of the pH range, staphylococci failed to grow, while the saprophytes grew under all of the conditions tested. At pH 5, the growth curves for the saprophytes were markedly altered from those obtained at neutral pH. The lag phases were greatly lengthened at and below 20 C, but normal numbers of saprophytes were reached in the stationary phase. At pH 6 and 8, staphylococcal growth showed the same inhibition observed at pH 7, at and below 20 C; normal multiplication was observed above this temperature, but with accelerated death phases. Thus, pH did not primarily effect staphylococcal growth through its influence on saprophyte growth and competition, but rather directly affected the growth of Staphylococcus cultures. Salt concentrations from 3.5 to 9.5% were investigated for influence on staphylococcal growth in mixed populations. Above 3.5% salt, staphylococcal inhibition at and above 20 C was not as marked as in the controls, although normal numbers were never reached. The saprophytes were increasingly inhibited, and their lag phases materially lengthened as salt concentration was increased. Salt acted directly on the Staphylococcus population and also, by repressing saprophyte growth, decreased competition, which allowed the staphylococci to grow. PMID:14106943

  2. Cooperation induced by random sequential exclusion

    NASA Astrophysics Data System (ADS)

    Li, Kun; Cong, Rui; Wang, Long

    2016-06-01

    Social exclusion is a common and powerful tool to penalize deviators in human societies, and thus to effectively elevate collaborative efforts. Current models on the evolution of exclusion behaviors mostly assume that each peer excluder independently makes the decision to expel the defectors, but has no idea what others in the group would do or how the actual punishment effect will be. Thus, a more realistic model, random sequential exclusion, is proposed. In this mechanism, each excluder has to pay an extra scheduling cost and then all the excluders are arranged in a random order to implement the exclusion actions. If one free rider has already been excluded by an excluder, the remaining excluders will not participate in expelling this defector. We find that this mechanism can help stabilize cooperation under more unfavorable conditions than the normal peer exclusion can do, either in well-mixed population or on social networks. However, too large a scheduling cost may undermine the advantage of this mechanism. Our work validates the fact that collaborative practice among punishers plays an important role in further boosting cooperation.

  3. ''Follow that quarkexclamation'' (and other exclusive stories)

    SciTech Connect

    Carroll, A.S.

    1987-06-17

    Quarks are considered to be the basic constituents of matter. In a series of recent experiments, Carroll studied exclusive reactions as a means of determining the interactions between quarks. Quantum Chromo-dynamics (QCD) is the modern theory of the interaction of quarks. This theory explains how quarks are held together via the strong interaction in particles known as hadrons. Hadrons consisting of three quarks are called baryons. Hadrons made up of a quark and an antiquark are called mesons. In his lecture, Carroll describes what happens when two hadrons collide and scatter to large angles. The violence of the collision causes the gluons that bind the quarks in a particular hadron to temporarily lose their grip on particular quarks. Quarks scramble toward renewed unity with other quarks, and they undergo rearrangement, which generally results in additional new particles. A two-body exclusive reaction has occurred when the same number of particles exist before and after the collisions. At large angles these exclusive reactions are very rare. The labels on the quarks known as flavor enable the experimenter to follow the history of individual quarks in detail during these exclusive reactions. Carroll describes the equipment used in the experiment to measure short distance, hard collisions at large angles. The collisions he discusses occur when a known beam of mesons or protons collide with a stationary proton target. Finally, Carroll summarizes what the experiments have shown from the study of exclusive reactions and what light some of their results shed on the theory of QCD.

  4. Exclusive Breastfeeding Experiences among Mexican American Women.

    PubMed

    Wambach, Karen; Domian, Elaine Williams; Page-Goertz, Sallie; Wurtz, Heather; Hoffman, Kelli

    2016-02-01

    According to the Centers for Disease Control and Prevention, Hispanic breastfeeding mothers begin early formula supplementation at higher rates than other ethnic groups, which can lead to shorter breastfeeding duration and decreased exclusive breastfeeding. Acculturation, the process of adopting beliefs and behaviors of another culture, appears to influence breastfeeding practices of Hispanic women in the United States. Little is known about Mexican American mothers' formula use and exclusive breastfeeding within the context of acculturation. Our study identified perceived benefits and barriers to exclusive breastfeeding and levels of acculturation among Mexican American women living in a Midwestern city. We used a qualitative descriptive design integrating Pender's Health Promotion Model concepts. Individual interviews were conducted in English or Spanish (N = 21). The revised Acculturation Rating Scale for Mexican Americans was used to examine acculturation levels. Acculturation scores indicated that the majority (66%) of the sample was "very Mexican oriented." Most women exclusively breastfed, with a few using early supplementation for "insufficient milk production." Three themes emerged: (1) It is natural that a woman give life and also provide the best food for her baby; (2) Breastfeeding is ultimately a woman's decision but is influenced by tradition, guidance, and encouragement; and (3) Breast milk is superior but life circumstances can challenge one's ability to breastfeed. Strong familial/cultural traditions supported and normalized breastfeeding. Barriers to exclusive breastfeeding were similar to breastfeeding women in general, in the United States. Findings support the need for culturally competent and individualized lactation care. © The Author(s) 2015.

  5. Competitive Intelligence and Social Advantage.

    ERIC Educational Resources Information Center

    Davenport, Elisabeth; Cronin, Blaise

    1994-01-01

    Presents an overview of issues concerning civilian competitive intelligence (CI). Topics discussed include competitive advantage in academic and research environments; public domain information and libraries; covert and overt competitive intelligence; data diversity; use of the Internet; cooperative intelligence; and implications for library and…

  6. Ion exclusion chromatography of aromatic acids.

    PubMed

    Mansour, Fotouh R; Kirkpatrick, Christine L; Danielson, Neil D

    2013-08-01

    The determination of aromatic acids by ion exclusion chromatography is challenging due to peak tailing and the long retention time of hydrophobic solutes. This review discusses the retention mechanisms and the factors affecting retention, eluents and detection methods used in ion exclusion chromatography of aromatic acids such as mono-, di-, tri- and tetra-carboxylic acids, amino acids, sulfonates and phenol. In addition, the different approaches used to improve the chromatographic separation of these compounds are also discussed. These approaches include introducing an internal gradient of the ionic strength, using vacancy ion exclusion chromatography, employing a hydrophilic cation exchange resin or adding a modifier such as heptanol to the dilute sulfuric acid mobile phase. The applications of these methods in the analysis of aromatic acids are provided with a table summarizing the stationary phases, the mobile phases and the detection methods.

  7. Delineating the roles of males and females in sperm competition

    PubMed Central

    Evans, Jonathan P.; Rosengrave, Patrice; Gasparini, Clelia; Gemmell, Neil J.

    2013-01-01

    Disentangling the relative roles of males, females and their interactive effects on competitive fertilization success remains a challenge in sperm competition. In this study, we apply a novel experimental framework to an ideally suited externally fertilizing model system in order to delineate these roles. We focus on the chinook salmon, Oncorhynchus tshawytscha, a species in which ovarian fluid (OF) has been implicated as a potential arbiter of cryptic female choice for genetically compatible mates. We evaluated this predicted sexually selected function of OF using a series of factorial competitive fertilization trials. Our design involved a series of 10 factorial crosses, each involving two ‘focal’ rival males whose sperm competed against those from a single ‘standardized’ (non-focal) rival for a genetically uniform set of eggs in the presence of OF from two focal females. This design enabled us to attribute variation in competitive fertilization success among focal males, females (OF) and their interacting effects, while controlling for variation attributable to differences in the sperm competitive ability of rival males, and male-by-female genotypic interactions. Using this experimental framework, we found that variation in sperm competitiveness could be attributed exclusively to differences in the sperm competitive ability of focal males, a conclusion supported by subsequent analyses revealing that variation in sperm swimming velocity predicts paternity success. Together, these findings provide evidence that variation in paternity success can be attributed to intrinsic differences in the sperm competitive ability of rival males, and reveal that sperm swimming velocity is a key target of sexual selection. PMID:24266039

  8. 42 CFR 402.13 - Penalty, assessment, and exclusion not exclusive.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Penalty, assessment, and exclusion not exclusive. 402.13 Section 402.13 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND... imposed under this part are in addition to any other penalties prescribed by law....

  9. 42 CFR 1003.108 - Penalty, assessment, and exclusion not exclusive.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Penalty, assessment, and exclusion not exclusive. 1003.108 Section 1003.108 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE, DEPARTMENT OF HEALTH... this part are in addition to any other penalties prescribed by law....

  10. 42 CFR 1003.108 - Penalty, assessment, and exclusion not exclusive.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 5 2013-10-01 2013-10-01 false Penalty, assessment, and exclusion not exclusive. 1003.108 Section 1003.108 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE, DEPARTMENT OF HEALTH... this part are in addition to any other penalties prescribed by law....

  11. 42 CFR 402.13 - Penalty, assessment, and exclusion not exclusive.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Penalty, assessment, and exclusion not exclusive. 402.13 Section 402.13 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND... imposed under this part are in addition to any other penalties prescribed by law....

  12. 75 FR 65614 - Availability for Non-Exclusive or Partially-Exclusive Licensing of Invention Concerning...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-26

    ... Department of the Army Availability for Non-Exclusive or Partially-Exclusive Licensing of Invention Concerning Obstetrics Simulation and Training Method System AGENCY: Department of the Army, DoD. ACTION... States Government, as represented by the Secretary of the Army, has rights to this invention....

  13. Exclusive B Decays to Charmonium Final States

    SciTech Connect

    Barrera, Barbara

    2000-10-13

    We report on exclusive decays of B mesons into final states containing charmonium using data collected with the BABAR detector at the PEP-II storage rings. The charmonium states considered here are J/{psi}, {psi}(2S), and {chi}{sub c1}. Branching fractions for several exclusive final states, a measurement of the decay amplitudes for the B{sup 0} {yields} J/{psi} K* decay, and measurements of the B{sup 0} and B{sup +} masses are presented. All of the results we present here are preliminary.

  14. Exclusive hadronic and nuclear processes in QCD

    SciTech Connect

    Brodsky, S.J.

    1985-12-01

    Hadronic and nuclear processes are covered, in which all final particles are measured at large invariant masses compared with each other, i.e., large momentum transfer exclusive reactions. Hadronic wave functions in QCD and QCD sum rule constraints on hadron wave functions are discussed. The question of the range of applicability of the factorization formula and perturbation theory for exclusive processes is considered. Some consequences of quark and gluon degrees of freedom in nuclei are discussed which are outside the usual domain of traditional nuclear physics. 44 refs., 7 figs. (LEW)

  15. Attention competition with advertisement.

    PubMed

    Cetin, Uzay; Bingol, Haluk O

    2014-09-01

    In the new digital age, information is available in large quantities. Since information consumes primarily the attention of its recipients, the scarcity of attention is becoming the main limiting factor. In this study, we investigate the impact of advertisement pressure on a cultural market where consumers have a limited attention capacity. A model of competition for attention is developed and investigated analytically and by simulation. Advertisement is found to be much more effective when the attention capacity of agents is extremely scarce. We have observed that the market share of the advertised item improves if dummy items are introduced to the market while the strength of the advertisement is kept constant.

  16. Attention competition with advertisement

    NASA Astrophysics Data System (ADS)

    Cetin, Uzay; Bingol, Haluk O.

    2014-09-01

    In the new digital age, information is available in large quantities. Since information consumes primarily the attention of its recipients, the scarcity of attention is becoming the main limiting factor. In this study, we investigate the impact of advertisement pressure on a cultural market where consumers have a limited attention capacity. A model of competition for attention is developed and investigated analytically and by simulation. Advertisement is found to be much more effective when the attention capacity of agents is extremely scarce. We have observed that the market share of the advertised item improves if dummy items are introduced to the market while the strength of the advertisement is kept constant.

  17. Rowing competitions and perspective

    NASA Astrophysics Data System (ADS)

    Flores, Alfinio; Bernhardt, Stephen A.; Shipman, Henry L.

    2015-02-01

    This paper is about integrating the use of graphing technology (specifically, GeoGebra) with principles of motion, principles of perspective, and the concept of vanishing points to model a dynamic event. Students were asked to analyse video images of a rowing competition filmed with a single camera positioned perpendicular to the race. The fixed position of the camera in such races makes it difficult to determine whether a scull closer to the camera is actually overtaking another, more distant scull. The paper illustrates how students in their first year at the university can integrate the use of technology, science, mathematics, and writing to solve a real world problem involving motion.

  18. House approves Competitiveness Bill

    NASA Astrophysics Data System (ADS)

    Bush, Susan

    After nearly 3 weeks of debate, the House approved the National Competitiveness Act of 1993 (HR820) on May 19. Subtitle B of the bill lays out specific roles for the National Science Foundation in supporting expansion of the agency's activities to include manufacturing technology development, worker training partnerships, and total quality management programs.Many geoscientists believe that this mandate runs contradictory to NSF's established mission of supporting basic research (Eos, April 13, 1993) and are concerned that basic research funds might be diverted to support manufacturing within the agency.

  19. Asymmetric and frequency-dependent pollinator-mediated interactions may influence competitive displacement in two vernal pool plants.

    PubMed

    Runquist, Ryan Briscoe; Stanton, Maureen L

    2013-02-01

    A plant species immigrating into a community may experience a rarity disadvantage due to competition for the services of pollinators. These negative reproductive interactions have the potential to lead to competitive displacement or exclusion of a species from a site. In this study, we used one- and two-species arrays of potted plants to test for density and frequency dependence in pollinator-mediated and above-ground intraspecific and interspecific competition between two species of Limnanthes that have overlapping ranges, but rarely occur in close sympatry. There were asymmetric competitive effects; the species responded differently to their frequency within 16-plant replacement series arrays. Limnanthes douglasii rosea experienced stronger reductions in lifetime and per-flower fertility, likely due to pollinator-mediated competition with Limnanthes alba. This effect may be linked to asymmetrical competition through heterospecific pollen transfer. This study demonstrates that pollinator-mediated competition may discourage establishment of L. d. rosea in sites already occupied by its congener.

  20. 42 CFR 402.214 - Appeal of exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CIVIL MONEY PENALTIES, ASSESSMENTS, AND EXCLUSIONS Exclusions § 402.214 Appeal of exclusion. (a... defenses that the person intends to assert. (4) Reasons why the proposed length of exclusion should...

  1. 42 CFR 402.214 - Appeal of exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CIVIL MONEY PENALTIES, ASSESSMENTS, AND EXCLUSIONS Exclusions § 402.214 Appeal of exclusion. (a... defenses that the person intends to assert. (4) Reasons why the proposed length of exclusion should...

  2. 42 CFR 402.209 - Scope and effect of exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Scope and effect of exclusion. 402.209 Section 402... effect of exclusion. (a) Scope of exclusion. Under this title, persons may be excluded from the Medicare, Medicaid, and, where applicable, any other Federal health care programs. (b) Effect of exclusion on...

  3. 42 CFR 1002.211 - Effect of exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Effect of exclusion. 1002.211 Section 1002.211 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OIG AUTHORITIES PROGRAM INTEGRITY-STATE-INITIATED EXCLUSIONS FROM MEDICAID Permissive Exclusions § 1002.211 Effect of exclusion. (a) Denial of payment. Except...

  4. 42 CFR 402.209 - Scope and effect of exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Scope and effect of exclusion. 402.209 Section 402.209 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS CIVIL MONEY PENALTIES, ASSESSMENTS, AND EXCLUSIONS Exclusions § 402.209 Scope and effect of exclusion. (a) Scope of...

  5. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Statutory exclusion. 551.214 Section 551.214 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY... customs officer who receives overtime pay under subsection (a) or premium pay under subsection (b) of 19...

  6. 21 CFR 110.19 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Exclusions. 110.19 Section 110.19 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION CURRENT GOOD MANUFACTURING PRACTICE IN MANUFACTURING, PACKING, OR HOLDING HUMAN FOOD...

  7. 21 CFR 110.19 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Exclusions. 110.19 Section 110.19 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION CURRENT GOOD MANUFACTURING PRACTICE IN MANUFACTURING, PACKING, OR HOLDING HUMAN FOOD...

  8. 21 CFR 110.19 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Exclusions. 110.19 Section 110.19 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION CURRENT GOOD MANUFACTURING PRACTICE IN MANUFACTURING, PACKING, OR HOLDING HUMAN FOOD...

  9. 40 CFR 503.6 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... treatment of domestic sewage in a treatment works. (i) Drinking water treatment sludge. This part does not... DISPOSAL OF SEWAGE SLUDGE General Provisions § 503.6 Exclusions. (a) Treatment processes. This part does... requirements for the use or disposal of sludge generated at an industrial facility during the treatment...

  10. 40 CFR 503.6 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... treatment of domestic sewage in a treatment works. (i) Drinking water treatment sludge. This part does not... DISPOSAL OF SEWAGE SLUDGE General Provisions § 503.6 Exclusions. (a) Treatment processes. This part does... requirements for the use or disposal of sludge generated at an industrial facility during the treatment...

  11. 40 CFR 503.6 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... treatment of domestic sewage in a treatment works. (i) Drinking water treatment sludge. This part does not... DISPOSAL OF SEWAGE SLUDGE General Provisions § 503.6 Exclusions. (a) Treatment processes. This part does... requirements for the use or disposal of sludge generated at an industrial facility during the treatment...

  12. 40 CFR 503.6 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... treatment of domestic sewage in a treatment works. (i) Drinking water treatment sludge. This part does not... DISPOSAL OF SEWAGE SLUDGE General Provisions § 503.6 Exclusions. (a) Treatment processes. This part does... requirements for the use or disposal of sludge generated at an industrial facility during the treatment...

  13. 40 CFR 503.6 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... treatment of domestic sewage in a treatment works. (i) Drinking water treatment sludge. This part does not... DISPOSAL OF SEWAGE SLUDGE General Provisions § 503.6 Exclusions. (a) Treatment processes. This part does... requirements for the use or disposal of sludge generated at an industrial facility during the treatment...

  14. Sexism and Permanent Exclusion from School

    ERIC Educational Resources Information Center

    Carlile, Anna

    2009-01-01

    Focussing on narratives collected during a two year participant observation research project in the children's services department of an urban local authority, this article addresses the intersection between incidents of permanent exclusion from school and assumptions made on the basis of a young person's gender. The article considers gendered…

  15. Exclusive breakup measurements for {sup 9}Be

    SciTech Connect

    Fulton, B.R.; Cowin, R.L.; Woolliscroft, R.J.; Clarke, N.M.; Donadille, L.; Freer, M.; Leask, P.J.; Singer, S.M.; Nicoli, M.P.; Benoit, B.; Hanappe, F.; Ninane, A.; Orr, N.A.; Tillier, J.; Stuttge, L.

    2004-10-01

    The first exclusive breakup measurements for the nucleus {sup 9}Be are presented. Breakup via several discrete states is observed following scattering off {sup 12}C and {sup 208}Pb. The results support the prediction of a recent microscopic cluster calculation for a strong n+{sup 8}Be(2{sup +}) state component in the second excited state.

  16. 29 CFR 9.4 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) Application to subcontracts. While the § 9.4(a)(1) exclusion applies to subcontracts that are less than the... section. (c) Federal service work constituting only part of employee's job. This part does not apply to... contracts as part of a single job, provided that the employees were not deployed in a manner that...

  17. 32 CFR 989.13 - Categorical exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Categorical exclusion. 989.13 Section 989.13 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION... Force-approved CATEXs is in appendix B. Supplements to this part may not add CATEXs or expand the scope...

  18. 32 CFR 989.13 - Categorical exclusion.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Categorical exclusion. 989.13 Section 989.13 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION... Force-approved CATEXs is in appendix B. Supplements to this part may not add CATEXs or expand the scope...

  19. 32 CFR 989.13 - Categorical exclusion.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Categorical exclusion. 989.13 Section 989.13 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION... Force-approved CATEXs is in appendix B. Supplements to this part may not add CATEXs or expand the scope...

  20. 32 CFR 989.13 - Categorical exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Categorical exclusion. 989.13 Section 989.13 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION... Force-approved CATEXs is in appendix B. Supplements to this part may not add CATEXs or expand the scope...