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. Competitive exclusion and coexistence of universal grammars.

    PubMed

    Mitchener, W Garrett; Nowak, Martin A

    2003-01-01

    Universal grammar (UG) is a list of innate constraints that specify the set of grammars that can be learned by the child during primary language acquisition. UG of the human brain has been shaped by evolution. Evolution requires variation. Hence, we have to postulate and study variation of UG. We investigate evolutionary dynamics and language acquisition in the context of multiple UGs. We provide examples for competitive exclusion and stable coexistence of different UGs. More specific UGs admit fewer candidate grammars, and less specific UGs admit more candidate grammars. We will analyze conditions for more specific UGs to outcompete less specific UGs and vice versa. An interesting finding is that less specific UGs can resist invasion by more specific UGs if learning is more accurate. In other words, accurate learning stabilizes UGs that admit large numbers of candidate grammars.

  3. 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,...

  4. 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,...

  5. 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.

  6. 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. PMID:27536943

  7. 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

  8. Coevolutionary games on networks.

    PubMed

    Ebel, Holger; Bornholdt, Stefan

    2002-11-01

    We study agents on a network playing an iterated Prisoner's dilemma against their neighbors. The resulting spatially extended coevolutionary game exhibits stationary states which are Nash equilibria. After perturbation of these equilibria, avalanches of mutations reestablish a stationary state. Scale-free avalanche distributions are observed that are in accordance with calculations from the Nash equilibria and a confined branching process. The transition from subcritical to critical avalanche dynamics can be traced to a change in the degeneracy of the cooperative macrostate and is observed for many variants of this game. PMID:12513567

  9. Competition between phytoplankton and bacteria: exclusion and coexistence.

    PubMed

    Grognard, Frédéric; Masci, Pierre; Benoît, Eric; Bernard, Olivier

    2015-04-01

    Resource-based competition between microorganisms species in continuous culture has been studied extensively both experimentally and theoretically, mostly for bacteria through Monod and Contois "constant yield" models, or for phytoplankton through the Droop "variable yield" models. For homogeneous populations of N bacterial species (Monod) or N phytoplanktonic species (Droop), with one limiting substrate and under constant controls, the theoretical studies indicated that competitive exclusion occurs: only one species wins the competition and displaces all the others (Armstrong and McGehee in Am Nat 115:151, 1980; Hsu and Hsu in SIAM J Appl Math 68:1600-1617, 2008). The winning species expected from theory is the one with the lowest "substrate subsistence concentration" s([star]), such that its corresponding equilibrium growth rate is equal to the dilution rate D. This theoretical result was validated experimentally with phytoplankton (Tilman and Sterner in Oecologia 61(2):197-200, 1984) and bacteria (Hansen and Hubell in Science 207(4438):1491-1493, 1980), and observed in a lake with microalgae (Tilman in Ecology 58(22):338-348, 1977). On the contrary for aggregating bacterial species described by a Contois model, theory predicts coexistence between several species (Grognard et al. in Discrete Contin Dyn Syst Ser B 8(1):73-93, 2007). In this paper we present a generalization of these results by studying a competition between three different types of microorganisms: planktonic (or free) bacteria (represented by a generalized Monod model), aggregating bacteria (represented by a Contois model) and free phytoplankton (represented by a Droop model). We prove that the outcome of the competition is a coexistence between several aggregating bacterial species with a free species of bacteria or phytoplankton, all the other free species being washed out. This demonstration is based mainly on the study of the substrate concentration's evolution caused by competition; it

  10. 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.

  11. 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.

  12. Comparison of mucosal competitive exclusion and competitive exclusion treatment to reduce Salmonella and Campylobacter spp. colonization in broiler chickens.

    PubMed

    Stern, N J; Cox, N A; Bailey, J S; Berrang, M E; Musgrove, M T

    2001-02-01

    Control of Salmonella spp. during the earliest phases of broiler production may provide the best opportunity to reduce human pathogens on processed broiler carcasses. Application of the "Nurmi concept" has been demonstrated to be an effective means in reducing Salmonella colonization among broiler chicks. In 1989, Aho et al. developed a competitive exclusion (CE) culture for control of Salmonella spp., whereas a mucosal competitive exclusion culture (MCE) developed in the United States was originally created to control Campylobacter colonization (Stern et al., 1995). The major differences in the two patents were the higher level of anaerobic culture required, the degree of epithelial scraping and washing of the ceca, media used for subculturing, and the culture incubation temperatures (35 C vs. 42 C). The CE and MCE were compared for efficacy in reducing Salmonella and Campylobacter colonization in broiler chicks. Nine adult birds (three for each of three replicates) were slaughtered, and each of a bird's paired ceca were used to produce corresponding antagonistic microflora, which were administered to day-of-hatch chicks. The chicks (a total of 210) were challenged 24 h later with Salmonella and Campylobacter and were killed 1 wk later, and levels of the pathogens were determined. Ninety CE-treated birds were significantly more colonized by Salmonella typhimurium than those 90 chicks treated with the MCE microflora (3.97 log 10 cfu/g cecal contents vs. 1.25 log 10 cfu/g cecal contents). Also, Campylobacter spp. colonization of these birds was significantly higher for CE-treated birds when compared with MCE-treated birds (6.96 log 10 cfu/g cecal contents vs. 5.03 log 10 cfu/g cecal contents). These results can be useful in developing intervention strategies to reduce chicken colonization by Salmonella and Campylobacter.

  13. Efficacy and food safety considerations of poultry competitive exclusion products.

    PubMed

    Wagner, Robert Doug

    2006-11-01

    Competitive exclusion (CE) products are anaerobic cultures of bacteria that are applied to poultry hatchlings to establish a protective enteric microbiota that excludes intestinal colonization by human food-borne pathogens. For safety of the poultry flock and human consumers, the identities of bacteria in CE products need to be known. A CE product is a culture of intestinal contents from adult chickens. It may be microbiologically defined by analysis of bacteria isolated from the culture, but many bacteria are hard to reliably isolate, identify, and characterize with conventional techniques. Sequence analysis of 16S ribosomal RNA (rRNA) genes may be more reliable than conventional techniques to identify CE bacteria. Bacteria in CE products may contain antimicrobial drug resistance and virulence mechanisms that could be transferred to the enteric bacteria of the food animal and to the human consumer. Detection methods for specific antimicrobial drug resistance and virulence genes and the integrase genes of conjugative transposons, mostly utilizing PCR technology, are being developed that can be applied to assess these risks in CE bacteria. With improvements in efficacy, bacterial identification, and detection and control of the possible risks of gene transfer, CE product technology can be made a more effective food safety tool.

  14. 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...

  15. 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.

  16. Dereplication by automated ribotyping of a competitive exclusion culture bacterial isolate library.

    PubMed

    Sheffield, Cynthia; Andrews, Kate; Harvey, Roger; Crippen, Tawni; Nisbet, David

    2006-01-01

    Concerns over the development of antibiotic-resistant bacteria within the food animal industry have intensified the search for natural approaches to the prevention and treatment of bacterial diseases. Competitive exclusion cultures are the foundation of a disease-management strategy based on the use of benign bacterial strains to prevent the establishment of pathogenic bacteria within a specific host. Differentiation of phenotypically ambiguous isolates is a critical step in establishing a manageable library of bacteria for use in the development of defined competitive exclusion cultures. We used automated ribotyping techniques to dereplicate a large collection of phenotypically ambiguous isolates from a continuous-flow competitive exclusion culture. A total of 157 isolates were screened following an EcoRI restriction enzyme digestion. The 157 isolates were resolved into 23 ribogroups, which represents an 85% reduction in the number of isolates in the bacterial isolate library. Seventy-six percent of the isolates fit into one of five ribogroups. This work demonstrated that automated ribotyping is an effective and efficient tool for dereplication of diverse bacterial isolate libraries.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. Competitive exclusion principle in ecology and absolute asymmetric synthesis in chemistry.

    PubMed

    Ribó, Josep M; Hochberg, David

    2015-10-01

    The key concepts underlying the Frank model (1953) for spontaneous asymmetric synthesis in chemistry are traced back to the pioneering works of Volterra (1926) and Lotka (1932) on biological species competition. The Lotka-Volterra (L-V) two-species exclusive competition model reduces to the Frank model for the special case of distinguishable but degenerate species (i.e., the enantiomers). The important ecological principle of competitive exclusion, originally derived from the L-V two-competitors model, is a consequence of sufficiently antagonistic interactions between the species competing for limited common resources, or mutual inhibition, as the term is known in the chemical literature on absolute asymmetric synthesis. The L-V and Frank models are described by the same general differential equations, nevertheless a crucial thermodynamic distinction between these models is necessary to correlate ecological selection and chemical selectivity arising from 1) the absence of reversibility in biological transformations, in marked contrast to chemical reactions, and 2) the constraints in chemical scenarios on the reaction rate constants required to fulfill the principle of micro-reversibility. PMID:26301597

  19. 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.

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

    DOE PAGESBeta

    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

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

    PubMed Central

    Luo, Shishi; Perelson, Alan S.

    2015-01-01

    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. PMID:26324897

  2. 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.

  3. Approach for selection of individual enteric bacteria for competitive exclusion in turkey poults.

    PubMed

    Bielke, L R; Elwood, A L; Donoghue, D J; Donoghue, A M; Newberry, L A; Neighbor, N K; Hargis, B M

    2003-09-01

    The intentional early colonization of the intestinal tract with beneficial microflora, known as competitive exclusion, has been shown to successfully protect poultry from selected enteric pathogens. Although effective cultures have been produced and are available, an inexpensive, air-tolerant, and completely defined culture is needed. Presently, we developed an in vitro competition assay to select for individual facultative anaerobes of poultry enteric origin that could exclude Salmonella. Using this assay, 24 isolates were selected and stored individually. These 24 isolates were amplified in batch culture (tryptic soy broth, 4 h at 40 degrees C) and administered at final dilutions of 10, 100, or 1,000 cfu to day-of-hatch poults. Forty-eight hours later, poults were challenged with 100 to 1,000 cfu antibiotic-resistance-marked Salmonella enteritidis PT 13A by oral gavage. Five days later, all poults were killed, and cecal tonsils were aseptically removed for tetrathionate enrichment (24 h at 37 degrees C) followed by selective plating with marker antibiotics. Selected lactose-negative, antibiotic-resistant colonies typical of Salmonella were further confirmed by serogrouping. Treatment-related protection ranged from 0 to 100% in three experiments. Greatest protection was related to the lowest concentrations of the protective microflora in each experiment. These data suggest that effective combinations of competitive enteric microflora can be identified by appropriate in vitro selection methods.

  4. 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. PMID:16014302

  5. Competitive exclusion in a multi-strain immuno-epidemiological influenza model with environmental transmission.

    PubMed

    Dang, Yan-Xia; Li, Xue-Zhi; Martcheva, Maia

    2016-12-01

    In this paper, a multi-strain model that links immunological and epidemiological dynamics across scales is formulated. On the within-host scale, the n strains eliminate each other with the strain having the largest immunological reproduction number persisting. However, on the population scale, we extend the competitive exclusion principle to a multi-strain model of SI-type for the dynamics of highly pathogenic flu in poultry that incorporates both the infection age of infectious individuals and biological age of pathogen in the environment. The two models are linked through the age-since-infection structure of the epidemiological variables. In addition the between-host transmission rate, the shedding rate of individuals infected by strain j and the disease-induced death rate depend on the within-host viral load. The immunological reproduction numbers [Formula: see text] and the epidemiological reproduction numbers [Formula: see text] are computed. By constructing a suitable Lyapunov function, the global stability of the infection-free equilibrium in the system is obtained if all reproduction numbers are smaller or equal to one. If [Formula: see text], the reproduction number of strain j is larger than one, then a single-strain equilibrium, corresponding to strain j exists. This single-strain equilibrium is globally stable whenever [Formula: see text] and [Formula: see text] is the unique maximal reproduction number and all of the reproduction numbers are distinct. That is, the strain with the maximal basic reproduction number competitively excludes all other strains. PMID:27608293

  6. 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. PMID:23437810

  7. Competitive Exclusion and Axiomatic Set-Theory: De Morgan's Laws, Ecological Virtual Processes, Symmetries and Frozen Diversity.

    PubMed

    Flores, J C

    2016-03-01

    This work applies the competitive exclusion principle and the concept of potential competitors as simple axiomatic tools to generalized situations in ecology. These tools enable apparent competition and its dual counterpart to be explicitly evaluated in poorly understood ecological systems. Within this set-theory framework we explore theoretical symmetries and invariances, De Morgan's laws, frozen evolutionary diversity and virtual processes. In particular, we find that the exclusion principle compromises the geometrical growth of the number of species. By theoretical extending this principle, we can describe interspecific depredation in the dual case. This study also briefly considers the debated situation of intraspecific competition. The ecological consequences of our findings are discussed; particularly, the use of our framework to reinterpret coupled mathematical differential equations describing certain ecological processes.

  8. Exclusive traveling waves for competitive reaction-diffusion systems and their stabilities

    NASA Astrophysics Data System (ADS)

    Leung, Anthony W.; Hou, Xiaojie; Li, Yi

    2008-02-01

    We study the existence, uniqueness and asymptotic behavior, as well as the stability of a special kind of traveling wave solutions for competitive PDE systems involving intrinsic growth, competition, crowding effects and diffusion. The traveling waves are exclusive in the sense that as the variable goes to positive or negative infinity, different species are close to extinction or carrying capacity. We perform an appropriate affine transformation of the traveling wave equations into monotone form and construct appropriate upper and lower solutions. By this means, we reduce the existence proof to application of well-known theory about monotone traveling wave systems (cf. [A. Leung, Systems of Nonlinear Partial Differential Equations: Applications to Biology and Engineering, MIA, Kluwer, Boston, 1989; J. Wu, X. Zou, Traveling wave fronts of reaction-diffusion systems with delay, J. Dynam. Differential Equations 13 (2001) 651-687] and [I. Volpert, V. Volpert, VE Volpert, Traveling Wave Solutions of Parabolic Systems, Transl. Math. Monogr., vol. 140, Amer. Math. Soc., Providence, RI, 1994]). Then, by using spectral analysis of the linearization over the profile, we prove the orbital stability of the traveling wave in some Banach spaces with exponentially weighted norm. Furthermore, we show that the introduction of some weight is necessary in the sense that, in general, traveling wave solutions with initial perturbations in the (unweighted) space C0 are unstable (cf. [I. Volpert, V. Volpert, V. Volpert, Traveling Wave Solutions of Parabolic Systems, Transl. Math. Monogr., vol. 140, Amer. Math. Soc., Providence, RI, 1994] and [D. Henry, Geometric Theory of Semilinear Parabolic Equations, Lecture Notes in Math., vol. 840, Springer-Verlag, New York, 1981]).

  9. The coevolutionary implications of host tolerance.

    PubMed

    Best, Alex; White, Andy; Boots, Mike

    2014-05-01

    Host tolerance to infectious disease, whereby hosts do not directly "fight" parasites but instead ameliorate the damage caused, is an important defense mechanism in both plants and animals. Because tolerance to parasite virulence may lead to higher prevalence of disease in a population, evolutionary theory tells us that while the spread of resistance genes will result in negative frequency dependence and the potential for diversification, the evolution of tolerance is instead likely to result in fixation. However, our understanding of the broader implications of tolerance is limited by a lack of fully coevolutionary theory. Here we examine the coevolution of tolerance across a comprehensive range of classic coevolutionary host-parasite frameworks, including equivalents of gene-for-gene and matching allele and evolutionary invasion models. Our models show that the coevolution of host tolerance and parasite virulence does not lead to the generation and maintenance of diversity through either static polymorphisms or through "Red-queen" cycles. Coevolution of tolerance may however lead to multiple stable states leading to sudden shifts in parasite impacts on host health. More broadly, we emphasize that tolerance may change host-parasite interactions from antagonistic to a form of "apparent commensalism," but may also lead to the evolution of parasites that are highly virulent in nontolerant hosts.

  10. 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. PMID:22928409

  11. Influence of bird strain on competitive exclusion of Campylobacter jejuni in young chicks.

    PubMed

    Laisney, M J; Gillard, M O; Salvat, G

    2004-02-01

    1. Newly hatched chicks of either layer or broiler strain were treated orally at regular intervals with either homologous or heterologous gut-flora preparations from young donor birds, in an attempt to prevent subsequent colonisation with Campylobacter jejuni by 'competitive exclusion' (CE). 2. Donors of 3 to 10 d of age were chosen to correspond with the period in which intensively reared poultry are least likely to become colonised with Campylobacter. 3. In two separate trials, material from donor layer hens (ISA Brown) protected male chicks of the same strain against a low (195 to 360 cfu/bird) Campylobacter challenge, but the same kind of material was ineffective when administered to chicks of a broiler strain (JA957). 4. Two further trials involved treatment preparations from young broilers, which failed to prevent Campylobacter colonisation of broiler chicks, even when colonisation occurred relatively slowly from a challenge of 90 to 94 cfu/bird. 5. It was concluded that any CE effect observed was strongly dependent on bird strain.

  12. 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.

  13. Competitive exclusion in a vector-host model for the dengue fever.

    PubMed

    Feng, Z; Velasco-Hernández, J X

    1997-05-01

    We study a system of differential equations that models the population dynamics of an SIR vector transmitted disease with two pathogen strains. This model arose from our study of the population dynamics of dengue fever. The dengue virus presents four serotypes each induces host immunity but only certain degree of cross-immunity to heterologous serotypes. Our model has been constructed to study both the epidemiological trends of the disease and conditions that permit coexistence in competing strains. Dengue is in the Americas an epidemic disease and our model reproduces this kind of dynamics. We consider two viral strains and temporary cross-immunity. Our analysis shows the existence of an unstable endemic state ('saddle' point) that produces a long transient behavior where both dengue serotypes cocirculate. Conditions for asymptotic stability of equilibria are discussed supported by numerical simulations. We argue that the existence of competitive exclusion in this system is product of the interplay between the host superinfection process and frequency-dependent (vector to host) contact rates.

  14. Coevolutionary dynamics in large, but finite populations

    NASA Astrophysics Data System (ADS)

    Traulsen, Arne; Claussen, Jens Christian; Hauert, Christoph

    2006-07-01

    Coevolving and competing species or game-theoretic strategies exhibit rich and complex dynamics for which a general theoretical framework based on finite populations is still lacking. Recently, an explicit mean-field description in the form of a Fokker-Planck equation was derived for frequency-dependent selection with two strategies in finite populations based on microscopic processes [A. Traulsen, J. C. Claussen, and C. Hauert, Phys. Rev. Lett. 95, 238701 (2005)]. Here we generalize this approach in a twofold way: First, we extend the framework to an arbitrary number of strategies and second, we allow for mutations in the evolutionary process. The deterministic limit of infinite population size of the frequency-dependent Moran process yields the adjusted replicator-mutator equation, which describes the combined effect of selection and mutation. For finite populations, we provide an extension taking random drift into account. In the limit of neutral selection, i.e., whenever the process is determined by random drift and mutations, the stationary strategy distribution is derived. This distribution forms the background for the coevolutionary process. In particular, a critical mutation rate uc is obtained separating two scenarios: above uc the population predominantly consists of a mixture of strategies whereas below uc the population tends to be in homogeneous states. For one of the fundamental problems in evolutionary biology, the evolution of cooperation under Darwinian selection, we demonstrate that the analytical framework provides excellent approximations to individual based simulations even for rather small population sizes. This approach complements simulation results and provides a deeper, systematic understanding of coevolutionary dynamics.

  15. Potential competitive exclusion bacteria from poultry inhibitory to Campylobacter jejuni and Salmonella.

    PubMed

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

    2007-04-01

    The objective of this study was to isolate from chickens potential competitive exclusion bacteria (CE) that are inhibitory to Campylobacter jejuni or Salmonella, or to both, for subsequent development of a defined CE product for use in poultry. Adult chickens from family farms, commercial farms, and broiler chicken research centers were sampled to identify and select C. jejuni-free donor chickens. A challenge treatment, which included administering perorally 106 CFU C. jejuni per chicken and determining undetectable cecal shedding of campylobacters at 4 weeks, was important for identifying the best CE donor chickens. Screening of bacterial colonies obtained from nine donor chickens by using selective and nonselective media yielded 636 isolates inhibitory to six C. jejuni strains in vitro, with 194 isolates being strongly inhibitory. Of the 194 isolates, 145 were from ceca, and 117 were facultative anaerobic bacteria. One hundred forty-three isolates were inhibitory to six strains of Salmonella (including five different serotypes) in vitro. Of these, 41 were strongly inhibitory to all C. jejuni and Salmonella strains evaluated, and most were Lactobacillus salivarius. A direct overlay method, which involved directly applying soft agar on plates with discrete colonies from mucus scrapings of gastrointestinal tracts, was more effective in isolating CE than was the frequently practiced isolation method of picking and transferring discrete colonies and then overlaying them with soft agar. The best approach for obtaining bacteria highly inhibitory to Salmonella and C. jejuni from chickens was to isolate bacteria from ceca under anaerobic conditions. Free-range chickens from family farms were better donors of potential CE strongly inhibitory to both Salmonella and Campylobacter than were chickens from commercial farms and broiler chicken research centers.

  16. 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. PMID:17477255

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  2. 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.

  3. Co-occurrence patterns of Bornean vertebrates suggest competitive exclusion is strongest among distantly related species.

    PubMed

    Beaudrot, Lydia; Struebig, Matthew J; Meijaard, Erik; van Balen, S; Husson, Simon; Marshall, Andrew J

    2013-11-01

    Assessing the importance of deterministic processes in structuring ecological communities is a central focus of community ecology. Typically, community ecologists study a single taxonomic group, which precludes detection of potentially important biotic interactions between distantly related species, and inherently assumes competition is strongest between closely related species. We examined distribution patterns of vertebrate species across the island of Borneo in Southeast Asia to assess the extent to which inter-specific competition may have shaped ecological communities on the island and whether the intensity of inter-specific competition in present-day communities varies as a function of evolutionary relatedness. We investigated the relative extent of competition within and between species of primates, birds, bats and squirrels using species presence-absence and attribute data compiled for 21 forested sites across Borneo. We calculated for each species pair the checkerboard unit value (CU), a statistic that is often interpreted as indicating the importance of interspecific competition. The percentage of species pairs with significant CUs was lowest in within-taxon comparisons. Moreover, for invertebrate-eating species the percentage of significantly checkerboarded species pairs was highest in comparisons between primates and other taxa, particularly birds and squirrels. Our results are consistent with the interpretation that competitive interactions between distantly related species may have shaped the distribution of species and thus the composition of Bornean vertebrate communities. This research highlights the importance of taking into account the broad mammalian and avian communities in which species occur for understanding the factors that structure biodiversity. PMID:23736548

  4. Gene flow and competitive exclusion of avian influenza A virus in natural reservoir hosts.

    PubMed

    Bahl, Justin; Vijaykrishna, Dhanasekaran; Holmes, Edward C; Smith, Gavin J D; Guan, Yi

    2009-08-01

    Geographical separation of host species has shaped the avian influenza A virus gene pool into independently evolving Eurasian and American lineages, although phylogenetic evidence for gene flow and reassortment indicates that these lineages also mix on occasion. While the evolutionary dynamics of the avian influenza gene pool have been described, the consequences of gene flow on virus evolution and population structure in this system have not been investigated. Here we show that viral gene flow from Eurasia has led to the replacement of endemic avian influenza viruses in North America, likely through competition for susceptible hosts. This competition is characterized by changes in rates of nucleotide substitution and selection pressures. However, the discontinuous distribution of susceptible hosts may produce long periods of co-circulation of competing virus strains before lineage extinction occurs. These results also suggest that viral competition for host resources may be an important mechanism in disease emergence.

  5. 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.

  6. The Evolution of Class Inequality in Higher Education: Competition, Exclusion, and Adaptation

    ERIC Educational Resources Information Center

    Alon, Sigal

    2009-01-01

    This study develops a comprehensive theoretical framework regarding the evolution of the class divide in postsecondary education. I conceptualize three prototypes of class inequality--effectively maintained, declining, and expanding--and associate their emergence with the level of competition in college admissions. I also unearth the twin…

  7. 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.

  8. 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.

  9. Combination of competitive exclusion and immunisation with a live Salmonella vaccine in newly hatched chickens: Immunological and microbiological effects.

    PubMed

    Braukmann, M; Barrow, P A; Berndt, A; Methner, U

    2016-08-01

    In addition to evaluating the efficacy potential of a combined use of vaccination and competitive exclusion (CE) against Salmonella exposure in chicks at 3-days of age, a live Salmonella Enteritidis vaccine (SE-LV) and a CE culture were tested for their ability to induce parameters of the innate immunity. Whereas the invasive SE-LV induced an influx of granulocytes and macrophages as well as an increased transcription of several cytokines in the caecal mucosa, the CE culture did not demonstrate any differences in these parameters compared to controls. It is therefore highly probable that the effects observed with CE cultures are not due to the rapid stimulation of the immune system. The combined use of both preparations did not result in an additive intestinal exclusion effect of the challenge strain more pronounced than that after single administration of the CE culture. The combined use of the Salmonella live vaccine and the CE culture resulted in an additive protective effect and prevented completely the systemic dissemination of the Salmonella challenge strain. To exploit the potential of combined use of CE and vaccination further and most effectively, live Salmonella vaccines are needed that are despite their attenuation in virulence still capable to induce both intestinal colonisation- and invasion-inhibition effects against Salmonella exposure. PMID:27473972

  10. 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.

  11. 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. PMID:24598426

  12. 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.

  13. Competitive Exclusion of Epiphytic Bacteria by IcePseudomonas syringae Mutants.

    PubMed

    Lindow, S E

    1987-10-01

    The growth of ice nucleation-active and near-isogenic ice nucleation-deficient (Ice) Pseudomonas syringae strains coexisting on leaf surfaces was examined to determine whether competition was sufficient to account for antagonism of phylloplane bacteria. The ice nucleation frequency spectra of 46 IceP. syringae mutants, obtained after mutagenesis with ethyl methanesulfonate, differed both quantitatively and qualitatively, but the mutants could be grouped into four distinct phenotypic classes. The numbers of ice nucleation-active bacteria and ice nuclei active at -5 degrees C were reduced on plants colonized with IceP. syringae mutant strains before challenge inoculations with an IceP. syringae wild-type strain. Frost injury to plants pretreated with IceP. syringae strains was also reduced significantly compared with that to control plants and was correlated with the population size of the IceP. syringae strain and with the numbers of ice nuclei active at -5 degrees C. An IceP. syringae strain colonized leaves, flowers, and young fruit of pears in field experiments and significantly reduced the colonization of these tissues by IceP. syringae strains and Erwinia amylovora as compared with untreated trees. PMID:16347468

  14. 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

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

    PubMed

    Wiles, Travis J; Jemielita, Matthew; Baker, Ryan P; Schlomann, Brandon H; Logan, Savannah L; Ganz, Julia; Melancon, Ellie; Eisen, Judith S; Guillemin, Karen; Parthasarathy, Raghuveer

    2016-07-01

    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

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. Competition between macroalgae and corals: effects of herbivore exclusion and increased algal biomass on coral survivorship and growth

    NASA Astrophysics Data System (ADS)

    Lirman, D.

    2001-05-01

    Recent declines in coral abundance accompanied by increases in macroalgal cover on Florida reefs highlight the importance of competition for space between these groups. This paper documents the frequency of coral-algal interactions on the Northern Florida Reef Tract and evaluates the effects of grazer exclusions and experimental algal addition on growth and tissue mortality of three coral species, Siderastrea siderea, Porites astreoides, and Montastraea faveolata. The frequency of interactions between corals and macroalgae was high as more than 50% of the basal perimeter of colonies was in contact with macroalgae; turf forms, Halimeda spp., and Dictyota spp. were the most common groups in contact with corals. Decreased grazing pressure resulted in significant increases in algal biomass within cages, and caged corals showed species-specific susceptibility to increased algal biomass. While no effects were detected for S. siderea, significant decreases in growth rates were documented for caged P. astreoides which had growth rates three to four times lower than uncaged colonies. When an algal addition treatment was included to duplicate maximum algal biomass levels documented for reefs in the area, colonies of P. astreoides in the algal addition treatment had growth rates up to ten times lower than uncaged colonies. High susceptibility to algal overgrowth was also found for the reef-building coral M. faveolata, which experienced significant tissue mortality under both uncaged (5.2% decrease in live tissue area per month) and caged (10.2% per month) conditions. The documented effects of increased algal biomass on coral growth and tissue mortality suggest a potential threat for the long-term survivorship and growth of corals in the Florida Reef Tract if present rates of algal growth and space utilization are maintained.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Cell surface-associated aggregation-promoting factor from Lactobacillus gasseri SBT2055 facilitates host colonization and competitive exclusion of Campylobacter jejuni.

    PubMed

    Nishiyama, Keita; Nakazato, Akiko; Ueno, Shintaro; Seto, Yasuyuki; Kakuda, Tsutomu; Takai, Shinji; Yamamoto, Yuji; Mukai, Takao

    2015-11-01

    Campylobacter jejuni, one of the most common causes of gastroenteritis worldwide, is transmitted to humans through poultry. We previously reported that Lactobacillus gasseri SBT2055 (LG2055) reduced C. jejuni infection in human epithelial cells in vitro and inhibited pathogen colonization of chickens in vivo. This suggested that the LG2055 adhesion and/or co-aggregation phenotype mediated by cell-surface aggregation-promoting factors (APFs) may be important for the competitive exclusion of C. jejuni. Here, we show that cell surface-associated APF1 promoted LG2055 self-aggregation and adhesion to human epithelial cells and exhibited high affinity for the extracellular matrix component fibronectin. These effects were absent in the apf1 knockout mutant, indicating the role of APF1 in LG2055-mediated inhibition of C. jejuni in epithelial cells and chicken colonization. Similar to APF1, APF2 promoted the co-aggregation of LG2055 and C. jejuni but did not inhibit C. jejuni infection. Our data suggest a pivotal role for APF1 in mediating the interaction of LG2055 with human intestinal cells and in inhibiting C. jejuni colonization of the gastrointestinal tract. We thus provide new insight into the health-promoting effects of probiotics and mechanisms of competitive exclusion in poultry. Further research is needed to determine whether the probiotic strains reach the epithelial surface.

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

    PubMed Central

    Ihara, Yasuo

    2011-01-01

    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. PMID:21320902

  9. 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. PMID:26348785

  10. 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.

  11. 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

  12. 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. PMID

  13. 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.

  14. A time and space complexity reduction for coevolutionary analysis of trees generated under both a Yule and Uniform model.

    PubMed

    Drinkwater, Benjamin; Charleston, Michael A

    2015-08-01

    The topology or shape of evolutionary trees and their unbalanced nature has been a long standing area of interest in the field of phylogenetics. Coevolutionary analysis, which considers the evolutionary relationships between a pair of phylogenetic trees, has to date not considered leveraging this unbalanced nature as a means to reduce the complexity of coevolutionary analysis. In this work we apply previous analyses of tree shapes to improve the efficiency of inferring coevolutionary events. In particular, we use this prior research to derive a new data structure for inferring coevolutionary histories. Our new data structure is proven to provide a reduction in the time and space required to infer coevolutionary events. It is integrated into an existing framework for coevolutionary analysis and has been validated using both synthetic and previously published biological data sets. This proposed data structure performs twice as fast as algorithms implemented using existing data structures with no degradation in the algorithm's accuracy. As the coevolutionary data sets increase in size so too does the running time reduction provided by the newly proposed data structure. This is due to our data structure offering a logarithmic time and space complexity improvement. As a result, the proposed update to existing coevolutionary analysis algorithms outlined herein should enable the inference of larger coevolutionary systems in the future.

  15. Behaviour change and competitive exclusion can explain the diverging HIV-1 and HIV-2 prevalence trends in Guinea-Bissau.

    PubMed

    Schmidt, W P; Van Der Loeff, M Schim; Aaby, P; Whittle, H; Bakker, R; Buckner, M; Dias, F; White, R G

    2008-04-01

    The aim of this study was to determine whether a temporary rise in sexual risk behaviour during war in Guinea-Bissau could explain the observed trends in HIV-1 and HIV-2 prevalence, and to explore the possible contribution of competitive elimination of HIV-2 by HIV-1. A simulation model of the heterosexual transmission of sexually transmitted infections was parameterized using demographic, behavioural and epidemiological data from rural Guinea-Bissau, and fitted to the observed HIV-1 and HIV-2 trends with and without a historic rise in risk behaviour. The observed trends could only be simulated by assuming a temporary rise in risk behaviour. Around 30% of the projected decline in HIV-2 prevalence from a peak of 8.7% to 4.3% in 2010 was due to competitive elimination by HIV-1. Importantly for public health, HIV-1 prevalence was predicted to continue increasing and to become the dominant HIV type by 2010. Data collection is required to validate this prediction.

  16. 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. PMID:21143330

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

    PubMed

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

    2016-07-01

    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 also the entire metabolome. Metabolomes are the final products of genotypes and are constrained 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 three closely related Pinus species with distant coevolutionary histories with the caterpillar of the processionary moth respond similarly to its attack. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of terpenes were in the attacked trees supporting the hypothesis that herbivores avoid plant individuals with higher concentrations. 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. PMID:27386082

  18. 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.

  19. 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.

  20. 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.

  1. Cooperation, conformity, and the coevolutionary problem of trait associations.

    PubMed

    Van Cleve, Jeremy

    2016-05-01

    In large scale social systems, coordinated or cooperative outcomes become difficult because encounters between kin or repeated encounters between friends are infrequent. Even punishment of noncooperators does not entirely alleviate the dilemma. One important mechanism for achieving cooperative outcomes in such social systems is conformist bias where individuals copy the behavior performed by the majority of their group mates. Conformist bias enhances group competition by both stabilizing behaviors within groups and increasing variance between groups. Due to this group competition effect, conformist bias is thought to have been an important driver of human social complexity and cultural diversity. However, conformist bias only evolves indirectly through associations with other traits, and I show that such associations are more difficult to obtain than previously expected. Specifically, I show that initial measures of population structure must be strong in order for a strong association between conformist bias and cooperative behaviors (cooperation and costly punishment) to evolve and for these traits to reach high frequencies. Additionally, the required initial level of association does not evolve de novo in simulations run over long timescales. This suggests that the coevolution of cooperative behaviors and conformist bias alone may not explain the high levels of cooperation within human groups, though conformist bias may still play an important role in combination with other social and demographic forces. PMID:26907203

  2. Cooperation, conformity, and the coevolutionary problem of trait associations.

    PubMed

    Van Cleve, Jeremy

    2016-05-01

    In large scale social systems, coordinated or cooperative outcomes become difficult because encounters between kin or repeated encounters between friends are infrequent. Even punishment of noncooperators does not entirely alleviate the dilemma. One important mechanism for achieving cooperative outcomes in such social systems is conformist bias where individuals copy the behavior performed by the majority of their group mates. Conformist bias enhances group competition by both stabilizing behaviors within groups and increasing variance between groups. Due to this group competition effect, conformist bias is thought to have been an important driver of human social complexity and cultural diversity. However, conformist bias only evolves indirectly through associations with other traits, and I show that such associations are more difficult to obtain than previously expected. Specifically, I show that initial measures of population structure must be strong in order for a strong association between conformist bias and cooperative behaviors (cooperation and costly punishment) to evolve and for these traits to reach high frequencies. Additionally, the required initial level of association does not evolve de novo in simulations run over long timescales. This suggests that the coevolution of cooperative behaviors and conformist bias alone may not explain the high levels of cooperation within human groups, though conformist bias may still play an important role in combination with other social and demographic forces.

  3. 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.

  4. Predicting protein folding rate change upon point mutation using residue-level coevolutionary information.

    PubMed

    Mallik, Saurav; Das, Smita; Kundu, Sudip

    2016-01-01

    Change in folding kinetics of globular proteins upon point mutation is crucial to a wide spectrum of biological research, such as protein misfolding, toxicity, and aggregations. Here we seek to address whether residue-level coevolutionary information of globular proteins can be informative to folding rate changes upon point mutations. Generating residue-level coevolutionary networks of globular proteins, we analyze three parameters: relative coevolution order (rCEO), network density (ND), and characteristic path length (CPL). A point mutation is considered to be equivalent to a node deletion of this network and respective percentage changes in rCEO, ND, CPL are found linearly correlated (0.84, 0.73, and -0.61, respectively) with experimental folding rate changes. The three parameters predict the folding rate change upon a point mutation with 0.031, 0.045, and 0.059 standard errors, respectively.

  5. 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

  6. The coevolutionary dynamics of obligate ant social parasite systems--between prudence and antagonism.

    PubMed

    Brandt, Miriam; Foitzik, Susanne; Fischer-Blass, Birgit; Heinze, Jürgen

    2005-05-01

    In this synthesis we apply coevolutionary models to the interactions between socially parasitic ants and their hosts. Obligate social parasite systems are ideal models for coevolution, because the close phylogenetic relationship between these parasites and their hosts results in similar evolutionary potentials, thus making mutual adaptations in a stepwise fashion especially likely to occur. The evolutionary dynamics of host-parasite interactions are influenced by a number of parameters, for example the parasite's transmission mode and rate, the genetic structure of host and parasite populations, the antagonists' migration rates, and the degree of mutual specialisation. For the three types of obligate ant social parasites, queen-tolerant and queen-intolerant inquilines and slavemakers, several of these parameters, and thus the evolutionary trajectory, are likely to differ. Because of the fundamental differences in lifestyle between these social parasite systems, coevolution should further select for different traits in the parasites and their hosts. Queen-tolerant inquilines are true parasites that exert a low selection pressure on their host, because of their rarity and the fact that they do not conduct slave raids to replenish their labour force. Due to their high degree of specialisation and the potential for vertical transmission, coevolutionary theory would predict interactions between these workerless parasites and their hosts to become even more benign over time. Queen-intolerant inquilines that kill the host queen during colony take-over are best described as parasitoids, and their reproductive success is limited by the existing worker force of the invaded host nest. These parasites should therefore evolve strategies to best exploit this fixed resource. Slavemaking ants, by contrast, act as parasites only during colony foundation, while their frequent slave raids follow a predator prey dynamic. They often exploit a number of host species at a given site, and

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

    PubMed Central

    Arachchilage, Madara Hetti; 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

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

    PubMed Central

    Beckett, Stephen J.; Williams, Hywel T. P.

    2013-01-01

    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. PMID:24516719

  10. Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites

    PubMed Central

    Noda, Satoko; Hongoh, Yuichi; Sato, Tomoyuki; Ohkuma, Moriya

    2009-01-01

    Background The microbial community in the gut of termites is responsible for the efficient decomposition of recalcitrant lignocellulose. Prominent features of this community are its complexity and the associations of prokaryotes with the cells of cellulolytic flagellated protists. Bacteria in the order Bacteroidales are involved in associations with a wide variety of gut protist species as either intracellular endosymbionts or surface-attached ectosymbionts. In particular, ectosymbionts exhibit distinct morphological patterns of the associations. Therefore, these Bacteroidales symbionts provide an opportunity to investigate not only the coevolutionary relationships with the host protists and their morphological evolution but also how symbiotic associations between prokaryotes and eukaryotes occur and evolve within a complex symbiotic community. Results Molecular phylogeny of 31 taxa of Bacteroidales symbionts from 17 protist genera in 10 families was examined based on 16S rRNA gene sequences. Their localization, morphology, and specificity were also examined by fluorescent in situ hybridizations. Although a monophyletic grouping of the ectosymbionts occurred in three related protist families, the symbionts of different protist genera were usually dispersed among several phylogenetic clusters unique to termite-gut bacteria. Similar morphologies of the associations occurred in multiple lineages of the symbionts. Nevertheless, the symbionts of congeneric protist species were closely related to one another, and in most cases, each host species harbored a unique Bacteroidales species. The endosymbionts were distantly related to the ectosymbionts examined so far. Conclusion The coevolutionary history of gut protists and their associated Bacteroidales symbionts is complex. We suggest multiple independent acquisitions of the Bacteroidales symbionts by different protist genera from a pool of diverse bacteria in the gut community. In this sense, the gut could serve as a

  11. Mathematical Physics of Complex Coevolutionary Systems: Theoretical Advances and Applications to Multiscale Hydroclimate Dynamics

    NASA Astrophysics Data System (ADS)

    Perdigão, Rui A. P.

    2016-04-01

    The fundamental stochastic-dynamic coevolution laws governing complex coevolutionary systems are introduced in a mathematical physics framework formally unifying nonlinear stochastic physics with fundamental deterministic interaction laws among spatiotemporally distributed processes. The methodological developments are then used to shed light onto fundamental interactions underlying complex spatiotemporal behaviour and emergence in multiscale hydroclimate dynamics. For this purpose, a mathematical physics framework is presented predicting evolving distributions of hydrologic quantities under nonlinearly coevolving geophysical processes. The functional formulation is grounded on first principles regulating the dynamics of each system constituent and their interactions, therefore its applicability is general and data-independent, not requiring local calibrations. Moreover, it enables the dynamical estimation of hydroclimatic variations in space and time from knowledge at different spatiotemporal conditions, along with the associated uncertainties. This paves the way for a robust physically based prediction of hydroclimatic changes in unsupervised areas (e.g. ungauged basins). Validation is achieved by producing, with the mathematical physics framework, a comprehensive spatiotemporal legacy consistent with the observed distributions along with their statistic-dynamic relations. The similarity between simulated and observed distributions is further assessed with novel robust nonlinear information-theoretic diagnostics. The present study brings to light emerging signatures of structural change in hydroclimate dynamics arising from nonlinear synergies across multiple spatiotemporal scales, and contributes to a better dynamical understanding and prediction of spatiotemporal regimes, transitions, structural changes and extremes in complex coevolutionary systems. This study further sheds light onto a diversity of emerging properties from harmonic to hyper-chaotic in general

  12. 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

  13. 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

  14. Competition-colonization trade-offs, competitive uncertainty, and the evolutionary assembly of species.

    PubMed

    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.

  15. 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

    2015-11-01

    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

  16. 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. PMID:27293783

  17. 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

    2015-11-01

    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.

  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. 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

  20. Connecting functional and statistical definitions of genotype by genotype interactions in coevolutionary studies

    PubMed Central

    Heath, Katy D.; Nuismer, Scott L.

    2014-01-01

    Predicting how species interactions evolve requires that we understand the mechanistic basis of coevolution, and thus the functional genotype-by-genotype interactions (G × G) that drive reciprocal natural selection. Theory on host-parasite coevolution provides testable hypotheses for empiricists, but depends upon models of functional G × G that remain loosely tethered to the molecular details of any particular system. In practice, reciprocal cross-infection studies are often used to partition the variation in infection or fitness in a population that is attributable to G × G (statistical G × G). Here we use simulations to demonstrate that within-population statistical G × G likely tells us little about the existence of coevolution, its strength, or the genetic basis of functional G × G. Combined with studies of multiple populations or points in time, mapping and molecular techniques can bridge the gap between natural variation and mechanistic models of coevolution, while model-based statistics can formally confront coevolutionary models with cross-infection data. Together these approaches provide a robust framework for inferring the infection genetics underlying statistical G × G, helping unravel the genetic basis of coevolution. PMID:24782890

  1. 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. PMID:20415533

  2. Learning tensegrity locomotion using open-loop control signals and coevolutionary algorithms.

    PubMed

    Iscen, Atil; Caluwaerts, Ken; Bruce, Jonathan; Agogino, Adrian; SunSpiral, Vytas; Tumer, Kagan

    2015-01-01

    Soft robots offer many advantages over traditional rigid robots. However, soft robots can be difficult to control with standard control methods. Fortunately, evolutionary algorithms can offer an elegant solution to this problem. Instead of creating controls to handle the intricate dynamics of these robots, we can simply evolve the controls using a simulation to provide an evaluation function. In this article, we show how such a control paradigm can be applied to an emerging field within soft robotics: robots based on tensegrity structures. We take the model of the Spherical Underactuated Planetary Exploration Robot ball (SUPERball), an icosahedron tensegrity robot under production at NASA Ames Research Center, develop a rolling locomotion algorithm, and study the learned behavior using an accurate model of the SUPERball simulated in the NASA Tensegrity Robotics Toolkit. We first present the historical-average fitness-shaping algorithm for coevolutionary algorithms to speed up learning while favoring robustness over optimality. Second, we use a distributed control approach by coevolving open-loop control signals for each controller. Being simple and distributed, open-loop controllers can be readily implemented on SUPERball hardware without the need for sensor information or precise coordination. We analyze signals of different complexities and frequencies. Among the learned policies, we take one of the best and use it to analyze different aspects of the rolling gait, such as lengths, tensions, and energy consumption. We also discuss the correlation between the signals controlling different parts of the tensegrity robot. PMID:25951199

  3. 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

  4. 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. PMID:23720546

  5. Host-parasite coevolutionary dynamics with generalized success/failure infection genetics.

    PubMed

    Engelstädter, Jan

    2015-05-01

    Host-parasite infection genetics can be more complex than envisioned by classic models such as the gene-for-gene or matching-allele models. By means of a mathematical model, I investigate the coevolutionary dynamics arising from a large set of generalized models of infection genetics in which hosts are either fully resistant or fully susceptible to a parasite, depending on the genotype of both individuals. With a single diploid interaction locus in the hosts, many of the infection genetic models produce stable or neutrally stable genotype polymorphisms. However, only a few models, which are all different versions of the matching-allele model, lead to sustained cycles of genotype frequency fluctuations in both interacting species ("Red Queen" dynamics). By contrast, with two diploid interaction loci in the hosts, many infection genetics models that cannot be classified as one of the standard infection genetics models produce Red Queen dynamics. Sexual versus asexual reproduction and, in the former case, the rate of recombination between the interaction loci have a large impact on whether Red Queen dynamics arise from a given infection genetics model. This may have interesting but as yet unexplored implications with respect to the Red Queen hypothesis for the evolution of sex.

  6. 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

  7. 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

  8. 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. PMID:27373339

  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. 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

  11. 47 CFR 73.5000 - Services subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following broadcast services are subject to competitive bidding: AM; FM; FM translator; analog television; low-power television; television translator; and Class A television. Mutually exclusive...

  12. 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.

  13. Coevolutionary, coexisting learning and teaching agents model for prisoner’s dilemma games enhancing cooperation with assortative heterogeneous networks

    NASA Astrophysics Data System (ADS)

    Tanimoto, Jun

    2013-07-01

    Unlike other natural network systems, assortativity can be observed in most human social networks, although it has been reported that a social dilemma situation represented by the prisoner’s dilemma favors dissortativity to enhance cooperation. We established a new coevolutionary model for both agents’ strategy and network topology, where teaching and learning agents coexist. Remarkably, this model enables agents’ enhancing cooperation more than a learners-only model on a time-frozen scale-free network and produces an underlying assortative network with a fair degree of power-law distribution. The model may imply how and why assortative networks are adaptive in human society.

  14. Sequence of host contact influences the outcome of competition among Aspergillus flavus isolates during host tissue invasion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biological control of aflatoxin contamination by Aspergillus flavus is achieved by competitive exclusion of aflatoxin producers by atoxigenic strains. However, factors dictating the extent to which competitive displacement occurs during host infection are unknown. The role of preemptive exclusion in...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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... 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...

  20. 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

  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. Sperm competition risk generates phenotypic plasticity in ovum fertilizability.

    PubMed

    Firman, Renée C; Simmons, Leigh W

    2013-12-01

    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.

  4. 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

  5. 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…

  6. Academic Competitions.

    ERIC Educational Resources Information Center

    Marin County Office of Education, San Rafael, CA.

    Descriptions of scholastic competitions for Marin County (California) students are presented. Following a rationale for conducting scholastic competitions, community groups and businesses which lend support are listed along with the type of support given. Participating grade levels, dates of competition during the 1983-84 school year, and a brief…

  7. 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

  8. Information use and resource competition: an integrative framework.

    PubMed

    Lee, Alexander E G; Ounsley, James P; Coulson, Tim; Rowcliffe, J Marcus; Cowlishaw, Guy

    2016-02-24

    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.

  9. Topology and sizing optimization of discrete structures using a cooperative coevolutionary genetic algorithm with independent ground structures

    NASA Astrophysics Data System (ADS)

    Zhong, Wei; Su, Ruiyi; Gui, Liangjin; Fan, Zijie

    2016-06-01

    This article proposes a method called the cooperative coevolutionary genetic algorithm with independent ground structures (CCGA-IGS) for the simultaneous topology and sizing optimization of discrete structures. An IGS strategy is proposed to enhance the flexibility of the optimization by offering two separate design spaces and to improve the efficiency of the algorithm by reducing the search space. The CCGA is introduced to divide a complex problem into two smaller subspaces: the topological and sizing variables are assigned into two subpopulations which evolve in isolation but collaborate in fitness evaluations. Five different methods were implemented on 2D and 3D numeric examples to test the performance of the algorithms. The results demonstrate that the performance of the algorithms is improved in terms of accuracy and convergence speed with the IGS strategy, and the CCGA converges faster than the traditional GA without loss of accuracy.

  10. 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 identifies ways in…

  11. 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

  12. Subinhibitory Antibiotic Concentrations Mediate Nutrient Use and Competition among Soil Streptomyces

    PubMed Central

    Vaz Jauri, Patricia; Bakker, Matthew G.; Salomon, Christine E.; Kinkel, Linda L.

    2013-01-01

    Though traditionally perceived as weapons, antibiotics are also hypothesized to act as microbial signals in natural habitats. However, while subinhibitory concentrations of antibiotics (SICA) are known to shift bacterial gene expression, specific hypotheses as to how SICA influence the ecology of natural populations are scarce. We explored whether antibiotic ‘signals’, or SICA, have the potential to alter nutrient utilization, niche overlap, and competitive species interactions among Streptomyces populations in soil. For nine diverse Streptomyces isolates, we evaluated nutrient utilization patterns on 95 different nutrient sources in the presence and absence of subinhibitory concentrations of five antibiotics. There were significant changes in nutrient use among Streptomyces isolates, including both increases and decreases in the capacity to use individual nutrients in the presence vs. in the absence of SICA. Isolates varied in their responses to SICA and antibiotics varied in their effects on isolates. Furthermore, for some isolate-isolate-antibiotic combinations, competition-free growth (growth for an isolate on all nutrients that were not utilized by a competing isolate), was increased in the presence of SICA, reducing the potential fitness cost of nutrient competition among those competitors. This suggests that antibiotics may provide a mechanism for bacteria to actively minimize niche overlap among competitors in soil. Thus, in contrast to antagonistic coevolutionary dynamics, antibiotics as signals may mediate coevolutionary displacement among coexisting Streptomyces, thereby hindering the emergence of antibiotic resistant phenotypes. These results contribute to our broad understanding of the ecology and evolutionary biology of antibiotics and microbial signals in nature. PMID:24339897

  13. Sequence co-evolutionary information is a natural partner to minimally-frustrated models of biomolecular dynamics

    PubMed Central

    Noel, Jeffrey K; Morcos, Faruck; Onuchic, Jose N

    2016-01-01

    Experimentally derived structural constraints have been crucial to the implementation of computational models of biomolecular dynamics. For example, not only does crystallography provide essential starting points for molecular simulations but also high-resolution structures permit for parameterization of simplified models. Since the energy landscapes for proteins and other biomolecules have been shown to be minimally frustrated and therefore funneled, these structure-based models have played a major role in understanding the mechanisms governing folding and many functions of these systems. Structural information, however, may be limited in many interesting cases. Recently, the statistical analysis of residue co-evolution in families of protein sequences has provided a complementary method of discovering residue-residue contact interactions involved in functional configurations. These functional configurations are often transient and difficult to capture experimentally. Thus, co-evolutionary information can be merged with that available for experimentally characterized low free-energy structures, in order to more fully capture the true underlying biomolecular energy landscape. PMID:26918164

  14. Increased competition may promote species coexistence.

    PubMed

    Vandermeer, J; Evans, M A; Foster, P; Höök, T; Reiskind, M; Wund, M

    2002-06-25

    It is a mainstay of community ecology that local exclusion of species will result if competitive pressures become too large. The pattern of exclusion may be complicated, but the qualitative orthodoxy has changed little since the pioneering work of Lotka, Volterra, and Gause--no two species can occupy the same niche. Stated in a more precise form, the higher the intensity of interspecific competition in an assemblage of species, the fewer the number of species that can coexist in perpetuity. We suggest that this orthodoxy results from "linear" thinking, and that if the classical equations are formulated more realistically with attendant nonlinearities, the orthodoxy breaks down and higher levels of competition may actually increase the likelihood that species will avoid competitive exclusion. Furthermore, this increased probability of coexistence at higher levels of competition is accompanied by characteristic dynamic patterns: (i) at lower levels of competition, after all extinction events have occurred, remaining species follow irregular chaotic patterns; (ii) at higher levels of competition, when most species coexist, all species are entrained in a single large limit cycle; (iii) the transient behavior appears to correspond to a special case of chaos, uniform phase chaotic amplitude.

  15. 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

  16. 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...

  17. Competitive morality.

    PubMed

    Roberts, Gilbert

    2013-02-01

    Baumard et al. argue that partner choice leads to fairness and mutualism, which then form the basis for morality. I comment that mutualism takes us only so far, and I apply the theory of competitive altruism in arguing how strategic investment in behaviours which make one a desirable partner may drive moral conduct.

  18. 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

  19. Interference competition and parasite virulence.

    PubMed Central

    Massey, Ruth C.; Buckling, Angus; ffrench-Constant, Richard

    2004-01-01

    Within-host competition between parasites, a consequence of infection by multiple strains, is predicted to favour rapid host exploitation and greater damage to hosts (virulence). However, the inclusion of biological variables can drastically change this relationship. For example, if competing parasite strains produce toxins that kill each other (interference competition), their growth rates and virulence may be reduced relative to single-strain infections. Bacteriocins are antimicrobial toxins produced by bacteria that target closely related strains and species, and to which the producing strain is immune. We investigated competition between bacteriocin-producing, insect-killing bacteria (Photorhabdus and Xenorhabdus) and how this competition affected virulence in caterpillars. Where one strain could kill the other, and not vice versa, the non-killing strain was competitively excluded, and insect mortality was the same as that of the killing strain alone. However, when caterpillars were multiply infected by strains that could kill each other, we did not observe competitive exclusion and their virulence was less than single-strain infections. The ubiquity and diversity of bacteriocins among pathogenic bacteria suggest mixed infections will be, on average, less virulent than single infections. PMID:15255095

  20. 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

  1. Picking battles wisely: plant behaviour under competition.

    PubMed

    Novoplansky, Ariel

    2009-06-01

    Plants are limited in their ability to choose their neighbours, but they are able to orchestrate a wide spectrum of rational competitive behaviours that increase their prospects to prevail under various ecological settings. Through the perception of neighbours, plants are able to anticipate probable competitive interactions and modify their competitive behaviours to maximize their long-term gains. Specifically, plants can minimize competitive encounters by avoiding their neighbours; maximize their competitive effects by aggressively confronting their neighbours; or tolerate the competitive effects of their neighbours. However, the adaptive values of these non-mutually exclusive options are expected to depend strongly on the plants' evolutionary background and to change dynamically according to their past development, and relative sizes and vigour. Additionally, the magnitude of competitive responsiveness is expected to be positively correlated with the reliability of the environmental information regarding the expected competitive interactions and the expected time left for further plastic modifications. Concurrent competition over external and internal resources and morphogenetic signals may enable some plants to increase their efficiency and external competitive performance by discriminately allocating limited resources to their more promising organs at the expense of failing or less successful organs.

  2. Malaysian competition

    SciTech Connect

    Jeffs, E.

    1994-11-01

    Two years ago, the first tentative steps were taken to privatize the Malaysian electricity supply industry with the flotation of 25 percent of Tenaga Nasional Bhd. At the same time the terms were defined for independent power generation, and plans were drawn up for six projects. Now, with six independent power producer projects under construction adding more capacity than the partly privatized TNB, the utility`s station managers are concerned they will be at a competitive disadvantage unless they can operate under the same type of power sales agreement.

  3. 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.

  4. 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

  5. Competition promotes the persistence of populations in ecosystems.

    PubMed

    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

  6. 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.

  7. 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

  8. Interference competition and species coexistence.

    PubMed Central

    Amarasekare, Priyanga

    2002-01-01

    Interference competition is ubiquitous in nature. Yet its effects on resource exploitation remain largely unexplored for species that compete for dynamic resources. Here, I present a model of exploitative and interference competition with explicit resource dynamics. The model incorporates both biotic and abiotic resources. It considers interference competition both in the classical sense (i.e. each species suffers a net reduction in per capita growth rate via interference from, and interference on, the other species) and in the broad sense (i.e. each species suffers a net reduction in per capita growth rate via interference from, but can experience an increase in growth rate via interference on, the other species). Coexistence cannot occur under classical interference competition even when the species inferior at resource exploitation is superior at interference. Such a trade-off can, however, change the mechanism of competitive exclusion from dominance by the superior resource exploiter to a priority effect. Now the inferior resource exploiter can exclude the superior resource exploiter provided it has a higher initial abundance. By contrast, when interference is beneficial to the interacting species, coexistence is possible via a trade-off between exploitation and interference. These results hold regardless of whether the resource is biotic or abiotic, indicating that the outcome of exploitative and interference competition does not depend on the exact nature of resource dynamics. The model makes two key predictions. First, species that engage in costly interference mechanisms (e.g. territoriality, overgrowth or undercutting, allelopathy and other forms of chemical competition) should not be able to coexist unless they also engage in beneficial interference mechanisms (e.g. predation or parasitism). Second, exotic invasive species that displace native biota should be superior resource exploiters that have strong interference effects on native species with little

  9. Punctuated Equilibrium in Statistical Models of Generalized Coevolutionary Resilience: How Sudden Ecosystem Transitions Can Entrain Both Phenotype Expression and Darwinian Selection

    NASA Astrophysics Data System (ADS)

    Wallace, Rodrick; Wallace, Deborah

    We argue that mesoscale ecosystem resilience shifts akin to sudden phase transitions in physical systems can entrain similarly punctuated events of gene expression on more rapid time scales, and, in part through such means, slower changes induced by selection pressure, triggering punctuated equilibrium Darwinian evolutionary transitions on geologic time scales. The approach reduces ecosystem, gene expression, and Darwinian genetic dynamics to a least common denominator of information sources interacting by crosstalk at markedly differing rates. Pettini's 'topological hypothesis', via a homology between information source uncertainty and free energy density, generates a regression-like class of statistical models of sudden coevolutionary phase transition based on the Rate Distortion and Shannon-McMillan Theorems of information theory which links all three levels. A mathematical treatment of Holling's extended keystone hypothesis regarding the particular role of mesoscale phenomena in entraining both slower and faster dynamical structures produces the result. A main theme is the necessity of a cognitive paradigm for gene expression, mirroring I. Cohen's cognitive approach to immune function. Invocation of the necessary conditions imposed by the asymptotic limit theorems of communication theory enables us to penetrate one layer more deeply before needing to impose an empirically-derived phenomenological system of 'Onsager relation' recursive coevolutionary stochastic differential equations. Extending the development to second order via a large deviations argument permits modeling the influence of human cultural structures on ecosystems as 'farming'.

  10. Complex competitive systems and competitive thermodynamics.

    PubMed

    Klimenko, A Y

    2013-01-13

    This publication reviews the framework of abstract competition, which is aimed at studying complex systems with competition in their generic form. Although the concept of abstract competition has been derived from a specific field--modelling of mixing in turbulent reacting flows--this concept is, generally, not attached to a specific phenomenon or application. Two classes of competition rules, transitive and intransitive, need to be distinguished. Transitive competitions are shown to be consistent (at least qualitatively) with thermodynamic principles, which allows for introduction of special competitive thermodynamics. Competitive systems can thus be characterized by thermodynamic quantities (such as competitive entropy and competitive potential), which determine that the predominant direction of evolution of the system is directed towards higher competitiveness. There is, however, an important difference: while conventional thermodynamics is constrained by its zeroth law and is fundamentally transitive, the transitivity of competitive thermodynamics depends on the transitivity of the competition rules. The analogy with conventional thermodynamics weakens as competitive systems become more intransitive, while strongly intransitive competitions can display types of behaviour associated with complexity: competitive cooperation and leaping cycles. Results of simulations demonstrating complex behaviour in abstract competitions are presented in the electronic supplementary material.

  11. 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.

  12. 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

  13. Competitive science: is competition ruining science?

    PubMed

    Fang, Ferric C; Casadevall, Arturo

    2015-04-01

    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.

  14. Competitive science: is competition ruining science?

    PubMed

    Fang, Ferric C; Casadevall, Arturo

    2015-04-01

    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

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Enhanced Information Exclusion Relations

    NASA Astrophysics Data System (ADS)

    Xiao, Yunlong; Jing, Naihuan; Li-Jost, Xianqing

    2016-07-01

    In Hall’s reformulation of the uncertainty principle, the entropic uncertainty relation occupies a core position and provides the first nontrivial bound for the information exclusion principle. Based upon recent developments on the uncertainty relation, we present new bounds for the information exclusion relation using majorization theory and combinatoric techniques, which reveal further characteristic properties of the overlap matrix between the measurements.

  20. 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.

  1. Enhanced Information Exclusion Relations.

    PubMed

    Xiao, Yunlong; Jing, Naihuan; Li-Jost, Xianqing

    2016-01-01

    In Hall's reformulation of the uncertainty principle, the entropic uncertainty relation occupies a core position and provides the first nontrivial bound for the information exclusion principle. Based upon recent developments on the uncertainty relation, we present new bounds for the information exclusion relation using majorization theory and combinatoric techniques, which reveal further characteristic properties of the overlap matrix between the measurements. PMID:27460975

  2. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... culture as a topical spray on each tray of 100 chicks (0.25 milliliter per chick). (2) Indications for use... to light for at least 5 minutes after spray treatment to encourage preening for oral uptake of the organisms. Provide access to feed and water as soon as possible after treatment. Do not...

  3. "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…

  4. Mixing, entropy and competition

    NASA Astrophysics Data System (ADS)

    Klimenko, A. Y.

    2012-06-01

    Non-traditional thermodynamics, applied to random behaviour associated with turbulence, mixing and competition, is reviewed and analysed. Competitive mixing represents a general framework for the study of generic properties of competitive systems and can be used to model a wide class of non-equilibrium phenomena ranging from turbulent premixed flames and invasion waves to complex competitive systems. We demonstrate consistency of the general principles of competition with thermodynamic description, review and analyse the related entropy concepts and introduce the corresponding competitive H-theorem. A competitive system can be characterized by a thermodynamic quantity—competitive potential—which determines the likely direction of evolution of the system. Contested resources tend to move between systems from lower to higher values of the competitive potential. There is, however, an important difference between conventional thermodynamics and competitive thermodynamics. While conventional thermodynamics is constrained by its zeroth law and is fundamentally transitive, the transitivity of competitive thermodynamics depends on the transitivity of the competition rules. Intransitivities are common in the real world and are responsible for complex behaviour in competitive systems. This work follows ideas and methods that have originated from the analysis of turbulent combustion, but reviews a much broader scope of issues linked to mixing and competition, including thermodynamic characterization of complex competitive systems with self-organization. The approach presented here is interdisciplinary and is addressed to the general educated readers, whereas the mathematical details can be found in the appendices.

  5. 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

  6. Strategic planning and competition

    SciTech Connect

    Gang, W.G. )

    1994-02-01

    This article discusses how to formulate a successful strategic plan in the face of competition from other electric utilities. Areas covered include reasons for plan failure, competitive simulations to test strategic plans, intelligence gathering, and cost reduction through reorganization.

  7. 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.

  8. 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.

  9. Enhanced Information Exclusion Relations

    PubMed Central

    Xiao, Yunlong; Jing, Naihuan; Li-Jost, Xianqing

    2016-01-01

    In Hall’s reformulation of the uncertainty principle, the entropic uncertainty relation occupies a core position and provides the first nontrivial bound for the information exclusion principle. Based upon recent developments on the uncertainty relation, we present new bounds for the information exclusion relation using majorization theory and combinatoric techniques, which reveal further characteristic properties of the overlap matrix between the measurements. PMID:27460975

  10. Competition in Courtship.

    ERIC Educational Resources Information Center

    Laner, Mary Riege

    1986-01-01

    Explores both positive and negative competition within premarital relationships using a typology of competitive behaviors. Findings compare competitive activities of men and women in serious mate-choice oriented relationships. Implications for both courtship and marital relationships are offered. (Author/BL)

  11. 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)

  12. Gaining the Competitive Edge.

    ERIC Educational Resources Information Center

    American Society for Training and Development, Alexandria, VA.

    Economic competitiveness is today's most critical issue. Keeping the United States competitive in the world marketplace means the difference between a rising standard of living for everyone and the disappearance of what is taken for granted as a way of life. Developing human capital is the route toward successful competition, as some examples…

  13. Competitive Anxiety in Sport.

    ERIC Educational Resources Information Center

    Martens, Rainer; And Others

    This book is a comprehensive review of competitive anxiety research that has used the Sport Competition Anxiety Test, or SCAT (a trait scale), and the Competitive State Anxiety Inventory-2 (CSAI-2). The book describes the theoretical basis and development procedures for both scales, including detailed information on reliability and validity. In…

  14. 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…

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 47 CFR 22.881 - Air-Ground Radiotelephone Service subject to competitive bidding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... exclusive initial applications for general aviation Air-Ground Radiotelephone Service licenses and mutually...) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air... competitive bidding. The general competitive bidding procedures set forth in part 1, subpart Q, of...

  1. 47 CFR 22.881 - Air-Ground Radiotelephone Service subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... exclusive initial applications for general aviation Air-Ground Radiotelephone Service licenses and mutually...) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air... competitive bidding. The general competitive bidding procedures set forth in part 1, subpart Q, of...

  2. 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.

  3. 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. PMID:17908245

  4. 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.

  5. Temperature- and Turbidity-Dependent Competitive Interactions Between Invasive Freshwater Mussels.

    PubMed

    Huang, Qihua; Wang, Hao; Ricciardi, Anthony; Lewis, Mark A

    2016-03-01

    We develop a staged-structured population model that describes the competitive dynamics of two functionally similar, congeneric invasive species: zebra mussels and quagga mussels. The model assumes that the population survival rates are functions of temperature and turbidity, and that the two species compete for food. The stability analysis of the model yields conditions on net reproductive rates and intrinsic growth rates that lead to competitive exclusion. The model predicts quagga mussel dominance leading to potential exclusion of zebra mussels at mean water temperatures below [Formula: see text] and over a broad range of turbidities, and a much narrower set of conditions that favor zebra mussel dominance and potential exclusion of quagga mussels at temperatures above [Formula: see text] and turbidities below 35 NTU. We then construct a two-patch dispersal model to examine how the dispersal rates and the environmental factors affect competitive exclusion and coexistence. PMID:26842390

  6. Temperature- and Turbidity-Dependent Competitive Interactions Between Invasive Freshwater Mussels.

    PubMed

    Huang, Qihua; Wang, Hao; Ricciardi, Anthony; Lewis, Mark A

    2016-03-01

    We develop a staged-structured population model that describes the competitive dynamics of two functionally similar, congeneric invasive species: zebra mussels and quagga mussels. The model assumes that the population survival rates are functions of temperature and turbidity, and that the two species compete for food. The stability analysis of the model yields conditions on net reproductive rates and intrinsic growth rates that lead to competitive exclusion. The model predicts quagga mussel dominance leading to potential exclusion of zebra mussels at mean water temperatures below [Formula: see text] and over a broad range of turbidities, and a much narrower set of conditions that favor zebra mussel dominance and potential exclusion of quagga mussels at temperatures above [Formula: see text] and turbidities below 35 NTU. We then construct a two-patch dispersal model to examine how the dispersal rates and the environmental factors affect competitive exclusion and coexistence.

  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. 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. PMID:25528318

  9. 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. PMID:26650073

  10. 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

  11. 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.

  12. Inclusive and Exclusive |Vub|

    SciTech Connect

    Petrella, Antonio; /Ferrara U. /INFN, Ferrara

    2011-11-17

    The current status of the determinations of CKM matrix element |V{sub ub}| via exclusive and inclusive charmless semileptonic B decays is reviewed. The large datasets collected at the B-Factories, and the increased precision of theoretical calculations have allowed an improvement in the determination of |V{sub ub}|. However, there are still significant uncertainties. In the exclusive approach, the most precise measurement of the pion channel branching ratio is obtained by an untagged analysis. This very good precision can be reached by tagged analyses with more data. The problem with exclusive decays is that the strong hadron dynamics can not be calculated from first principles and the determination of the form factor has to rely on light-cone sum rules or lattice QCD calculations. The current data samples allow a comparison of different FF models with data distributions. With further developments on lattice calculations, the theoretical error should shrink to reach the experimental one. The inclusive approach still provides the most precise |V{sub ub}| determinations. With new theoretical calculations, the mild (2.5{sigma}) discrepancy with respect to the |V{sub ub}| value determined from the global UT fit has been reduced. As in the exclusive approach, theoretical uncertainties represent the limiting factor to the precision of the measurement. Reducing the theoretical uncertainties to a level comparable with the statistical error is challenging. New measurements in semileptonic decays of charm mesons could increase the confidence in theoretical calculations and related uncertainties.

  13. 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.…

  14. Competitive coexistence of two Pneumocystis species.

    PubMed

    Icenhour, Crystal R; Arnold, Jonathan; Medvedovic, Mario; Cushion, Melanie T

    2006-05-01

    Pneumocystis are fungal pathogens of mammalian lungs that can cause lethal pneumonia in immunocompromised hosts. In some mammals, coinfections of genetically distinct Pneumocystis populations have been identified, but the nature of their interaction and its significance are unknown. Two species that infect rats, Pneumocystis carinii and Pneumocystis wakefieldiae, were studied over a 6-year period, representing approximately 700 generations of Pneumocystis. Population densities of each species were analyzed within the framework of the Lotka-Volterra competition model, which revealed the two species were in competition and predicted competitive exclusion of one species. However, stable coexistence was observed in 460 replicate populations. Selected extrinsic factors that might mitigate the extinction were evaluated. Logistic-regression analyses showed that higher relative humidity and higher organism lung burdens were associated with infections comprised of P. carinii alone, while lower temperatures and an increased rat census were associated with the presence of P. wakefieldiae. PCR and immunofluorescent analysis of rat lung tissue showed that both species were present within the same alveoli, excluding habitat heterogeneity as a mechanism of coexistence. These data suggest that P. carinii and P. wakefieldiae were in competitive coexistence, which was influenced in part by extrinsic factors. To our knowledge, this is the first report to evaluate interactions of pathogenic fungal species within a mammalian host using ecological models. PMID:15949973

  15. 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.…

  16. Competition in Economic Theory.

    ERIC Educational Resources Information Center

    Livesey, F.

    1982-01-01

    Considers two alternative views of competition found in the economics literature. The author demonstrates that these alternative views of competition underlie alternative views in other areas of economics, including welfare economics and micro-economic policy. Implications for college students and teachers are examined. (Author/AM)

  17. 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…

  18. Testing a simple rule for dominance in resource competition.

    PubMed

    Fox, Jeremy W

    2002-03-01

    Competition for limiting resources long has been considered an important factor generating community structure. A minimal model of resource competition predicts that the species that reduces the limiting resource R to the lowest level ([Formula: see text]) will exclude its competitors. Whether this "[Formula: see text] rule" is robust to violations of model assumptions remains largely unknown. I conducted a competition experiment with four species of bacterivorous protists in laboratory microcosms and predicted the outcome from each species' [Formula: see text] value. I also examined how the outcome of competition, species abundances, and the effect of protists on bacterial density varied with productivity. Microcosms were unstirred batch cultures containing a variety of bacteria, challenging the robustness of the simplest competition models. Protists with low [Formula: see text] values were less affected by competition, although competing protists often coexisted. The values of [Formula: see text] can predict competitive dominance, even in the absence of competitive exclusion. Other model predictions were less robust. Contrary to expectation, densities of grazed bacteria increased with productivity, and the effect of some protists on bacterial density did not vary with productivity. Bacterial heterogeneity may account for deviations from model predictions. Further experiments should examine the conditions under which simple rules can be expected to identify dominant species.

  19. 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

  20. 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.

  1. 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. PMID:26831111

  2. 75 FR 80798 - Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of Inventions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-23

    ... Department of the Army Availability for Exclusive, Non-Exclusive, or Partially-Exclusive Licensing of... AGENCY: Department of the Army, DoD. ACTION: Notice. SUMMARY: Announcement is made of the availability... of the Army, has rights to this invention. ADDRESSES: Commander, U.S. Army Medical Research...

  3. 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.

  4. 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

  5. Social exclusion in finite populations.

    PubMed

    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. PMID:25974550

  6. Social exclusion in finite populations.

    PubMed

    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.

  7. 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.

  8. Justice and competitive markets.

    PubMed

    Brody, B A

    1987-02-01

    This essay challenges the view that the provision of health care must take place within a competitive-free system. The author argues that, presuming that there is a requirement to meet the demands of those who cannot pay for health care, a competitive market provides a good way to deal with injustices within the health care system. The author concludes that the demands for justice are best met when indigent individuals use some portion of the funds they receive from the government to purchase one of the many competing forms of health care. This scheme requires a competitive market in the delivery of health care.

  9. 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.

  10. Coexistence in a competitive parasitoid-host system.

    PubMed

    Castillo, Derik; Velasco-Hernández, Jorge X

    2003-03-01

    The main objective of this work is to determine the conditions for coexistence and competitive exclusion in a discrete model for a community of three species: a stage-structured host and two competing parasitoids sharing the same host developmental stage. Coexistence of the community of the species is found to depend on the host life history parameters in the first place, and on competitive ability and parasitoid efficiency in the second place. In particular, parasitoids equilibrium densities are defined by the size of the refuge. Extinction is expected with low growth rate and with low adult survival. Host life histories are also associated with oscillations in population density, and depending on the combination of host adult survival from one generation to the next and host growth rate, the minimum of fluctuations approaches zero, implying a higher potential risk of extinction because of stochastic factors. Our results suggest that equally reduced survival of parasitoids in hosts parasitized by both species determines extinction of the parasitoid with lower population density, in contrast to the case when both parasitoids benefit with 50% of all doubly parasitized hosts, leading to the hypothesis that a community where competitors in multiparasitized hosts die, easily becomes extinct. Competitive exclusion is expected for highly asymmetric competitive interactions, independent of population densities, allowing us to hypothesize that coexistence of competitors in systems with limited resources and refuges is associated with a clearly defined competitive hierarchy.

  11. Costing and competition.

    PubMed

    Bates, K; Brignall, S

    1994-01-01

    Working for patients established a new system of contracts between providers and purchasers of healthcare, with prices based on full costs, avoiding cross-subsidization. The new regime necessitates greatly improved costing systems, to improve the efficiency of service provision by creating price competition between providers. Ken Bates and Stan Brignall argue that non-price competition also occurs, with providers 'differentiating' on quality of service/product, flexibility or innovation. PMID:10136091

  12. 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.

  13. 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.

  14. 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…

  15. Untangling healthcare competition.

    PubMed

    Harris, I C; McDaniel, R R

    1993-11-01

    Traditional approaches to competition may be inappropriate for healthcare providers. Neoclassical economics makes the implicit assumption that a single actor embodies consumption, compensation, and benefit from a transaction. In healthcare, this assumption does not hold. Instead, such actions are accomplished by three separate actors--consumers (physicians), customers (third-party payers), and clients (patients). A hospital simultaneously competes in three arenas. Hospitals compete for physicians along a technological dimension. Competition for third-party payers takes on a financial dimension. Hospitals compete for patients along a marketing dimension. Because of the complex marketplace interactions among hospital, patient, physician, and third-party payer, the role of price in controlling behavior is difficult to establish. The dynamics underlying the hospital selection decision--that is, the decision maker's expectations of services and the convenience of accessing services--must also be considered. Healthcare managers must understand the interrelationships involved in the three-pronged competitive perspective for several reasons. This perspective clarifies the multiple facets of competition a hospital faces. It also disentangles the actions previously fulfilled by the traditional single buyer. It illuminates the critical skills underlying the competition for each audience. Finally, it defines the primary criterion each audience uses in sorting among hospitals. Recognition of the multifaceted nature of competition among healthcare providers will help demystify market behavior and thereby improve internal organizational communication systems, managers' ability to focus on appropriate activities, and the hospital's ability to adapt to changing market conditions.

  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. 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. PMID:25811338

  18. 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.

  19. Mutual exclusivity and exclusion: Converging evidence from two contrasting traditions

    PubMed Central

    Huntley, Kenneth R.; Ghezzi, Patrick M.

    1993-01-01

    Mutual exclusivity and exclusion are two terms used by cognitive psychologists and behavior analysts, respectively, to identify essentially the same phenomenon. While cognitive psychologists view mutual exclusivity in terms of a hypothesis that individuals use intuitively while acquiring language, behavior analysts regard exclusion as a derived stimulus relation that bears upon the acquisition and elaboration of verbal behavior. Each research tradition, though at odds with respect to accounting for the phenomenon, employs similar procedures to answer comparable questions. Insofar as both cognitive and behavioral psychologists are studying the same phenomenon, the ground work is established for collaboration between them. PMID:22477081

  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. Hard Exclusive Pion Leptoproduction

    NASA Astrophysics Data System (ADS)

    Kroll, Peter

    2016-08-01

    In this talk it is reported on an analysis of hard exclusive leptoproduction of pions within the handbag approach. It is argued that recent measurements of this process performed by HERMES and CLAS clearly indicate the occurrence of strong contributions from transversely polarized photons. Within the handbag approach such γ ^{ *}_T→ π transitions are described by the transversity GPDs accompanied by twist-3 pion wave functions. It is shown that the handbag approach leads to results on cross sections and single-spin asymmetries in fair agreement with experiment. Predictions for other pseudoscalar meson channels are also briefly discussed.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. Utility competition and residential customers

    SciTech Connect

    Studness, C.M.

    1994-11-01

    Residential customers have found themselves either ignored or ill-used by the major participants in the struggle over utility competition. No group is seeking to secure them the benefits of competition, and those who oppose competition have curried their favor by conjuring up misleading horror stories about how competition would harm them. Yet residential customers ultimately stand to gain as much from competition as larger customers.

  10. 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.

  11. 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.

  12. Competition in the Classroom.

    ERIC Educational Resources Information Center

    Napier, Erv

    1981-01-01

    Argues that teacher use of competition in the classroom may lead to anxiety, aggression, or a decrease in self-concept among students and that learning to compete is not so important in a postindustrial society. Advocates cooperative classroom activities. (SJL)

  13. Cost and competition

    SciTech Connect

    Kahn, E.

    1994-11-01

    The growth of private power is part of the movement away from administrative regulation and toward competitive control of prices for electricity. Despite the substantial success of the private power industry, this process is far from complete. Utility regulators, who preside over the power purchase contracting process, are responsible for assuring that the prices which are presented to them for approval are reasonable.

  14. 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…

  15. 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…

  16. 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.…

  17. 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…

  18. 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…

  19. 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…

  20. 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…

  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. 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…

  3. 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.

  4. 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)…

  5. 47 CFR 73.5002 - Application and certification procedures; return of mutually exclusive applications not subject...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Application and certification procedures; return of mutually exclusive applications not subject to competitive bidding procedures; prohibition of collusion. 73.5002 Section 73.5002 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST...

  6. Mating behaviour, life history and adaptation to insecticides determine species exclusion between whiteflies.

    PubMed

    Crowder, David W; Horowitz, A Rami; De Barro, Paul J; Liu, Shu-Sheng; Showalter, Ann M; Kontsedalov, Svetlana; Khasdan, Vadim; Shargal, Amihai; Liu, Jian; Carrière, Y

    2010-05-01

    1. Negative interspecific interactions, such as resource competition or reproductive interference, can lead to the displacement of species (species exclusion). 2. Here, we investigated the effect of life history, mating behaviour and adaptation to insecticides on species exclusion between cryptic whitefly species that make up the Bemisia tabaci species complex. We conducted population cage experiments independently in China, Australia, the United States and Israel to observe patterns of species exclusion between an invasive species commonly referred to as the B biotype and three other species commonly known as biotypes ZHJ1, AN and Q. 3. Although experimental conditions and species varied between regions, we were able to predict the observed patterns of exclusion in each region using a stochastic model that incorporated data on development time, mating behaviour and resistance to insecticides. 4. Between-species variation in mating behaviour was a more significant factor affecting species exclusion than variation in development time. Specifically, the ability of B to copulate more effectively than other species resulted in a faster rate of population increase for B, as well as a reduced rate of population growth for other species, leading to species exclusion. The greater ability of B to evolve resistance to insecticides also contributed to exclusion of other species in some cases. 5. Results indicate that an integrative analysis of the consequences of variation in life-history traits, mating behaviours and adaption to insecticides could provide a robust framework for predicting species exclusion following whitefly invasions.

  7. 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.

  8. 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.

  9. Exclusive contracts in the hospital setting: a two-edged sword, part 1: legal issues.

    PubMed

    Portman, Robert M

    2007-05-01

    Hospitals routinely enter into contracts with radiology groups for the right to be the exclusive provider of radiology services at the facility in exchange for the group agreeing to provide and manage all aspects of that service within the hospital. These "exclusive contracts" generally result in the radiology department and associated equipment being closed off to physicians who are not part of the contracting group. Exclusive contracts are generally considered to be good for physicians who have them and bad for those excluded by them. In fact, while exclusive contracts offer obvious benefits to the physicians who receive them and obvious disadvantages for those who are excluded, they also present pitfalls for physicians in the chosen group. Part I of this article discusses the legal issues raised by exclusive contracts. Although these agreements appear to be anti-competitive, most courts have rejected antitrust challenges to exclusive contracts. Excluded physicians have had much greater success in attacking exclusive contracting arrangements on breach of contract and procedural/due process grounds. Exclusive contracting arrangements can also raise concerns under the Medicare-Medicaid anti-kickback statute if the contracting physicians are required to pay consideration or accept less than fair market value compensation in exchange for exclusive contracts. These agreements can also raise issues under the Stark II physician self-referral law if the contracting physicians are in a position to refer Medicare or Medicaid patients to the hospital. Part II of this article will discuss the advantages and disadvantages of exclusive contracts for physicians covered and not covered by such contracts, as well as strategies for avoiding them or minimizing their potential adverse impact. It also will discuss specific provisions of exclusive contracts that should be included or avoided.

  10. 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.

  11. 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. PMID:23595418

  12. 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)

  13. Delineating the roles of males and females in sperm competition.

    PubMed

    Evans, Jonathan P; Rosengrave, Patrice; Gasparini, Clelia; Gemmell, Neil J

    2013-12-01

    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.

  14. 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…

  15. Hospital survival in a competitive environment: the competitive constituency model.

    PubMed

    Ehreth, J

    1993-01-01

    Organizational theory is extended to develop a method for administrators to assess hospital effectiveness in a competitive environment. First, the literature pertaining to organizational effectiveness and survival is synthesized to show the lack of consideration for the effects of competition. Second, the article integrates the effects of competition on organizational effectiveness through a competitive constituency model. A step-by-step procedure is proposed to apply the theory in an organizational setting. The model explicitly addresses differences in power relations between hospitals, their competition, and their stakeholders. The relative nature of effectiveness is explored by comparing the hospital to its competition using criteria developed through specific goals of stakeholders. The distinction between managerial and organizational effectiveness constructs is clarified. Finally, the practical application of this model is demonstrated by assessing the effectiveness of a hospital in the competitive environment of Seattle, Washington, where two hospitals have recently closed.

  16. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 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 to... 47 Telecommunication 5 2011-10-01 2011-10-01 false 800 MHz SMR spectrum subject to...

  17. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 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 to... 47 Telecommunication 5 2012-10-01 2012-10-01 false 800 MHz SMR spectrum subject to...

  18. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 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 to... 47 Telecommunication 5 2014-10-01 2014-10-01 false 800 MHz SMR spectrum subject to...

  19. 47 CFR 90.901 - 800 MHz SMR spectrum subject to competitive bidding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 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 to... 47 Telecommunication 5 2010-10-01 2010-10-01 false 800 MHz SMR spectrum subject to...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 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 to... 47 Telecommunication 5 2013-10-01 2013-10-01 false 800 MHz SMR spectrum subject to...

  1. Competitive epidemic spreading over arbitrary multilayer networks

    NASA Astrophysics Data System (ADS)

    Darabi Sahneh, Faryad; Scoglio, Caterina

    2014-06-01

    This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI1SI2S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.

  2. Competitive epidemic spreading over arbitrary multilayer networks.

    PubMed

    Darabi Sahneh, Faryad; Scoglio, Caterina

    2014-06-01

    This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI_{1}SI_{2}S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.

  3. The two sides of competition: competition-induced effort and affect during intergroup versus interindividual competition.

    PubMed

    Wittchen, Marion; Krimmel, Anna; Kohler, Mischa; Hertel, Guido

    2013-08-01

    Competition strongly affects individual effort and performance for both individuals and groups. Especially in work settings, these effort gains might come at the cost of individual well-being. The present study tested whether competition increases both effort (as indicated by task performance) and stress (in terms of cardiovascular reactivity and affective response), and whether this effect is further qualified by the type of competition (interindividual vs. intergroup), using a cognitive computer-based task and a 2 (Group: Yes, No) × 2 (Competition: Yes, No) × 2 (Gender) factorial design (N = 147). All participants either worked as a representative of a group or as an individual, and were offered performance-related incentives distributed in a lottery. In the competition conditions, participants were informed that they competed with someone else, and that only the winning person/team would take part in the lottery. Consistent with expectations, competition increased both individual effort and cardiovascular reactivity compared to non-competitive work. Moreover, for female participants, intergroup competition triggered increased effort and more positive affect than interindividual competition. Aside from documenting costly side-effects of competition in terms of stress, this study provides evidence for a stress-related explanation of effort gains during intergroup competition as compared to interindividual competition.

  4. The role of drought- and disturbance-mediated competition in shaping community responses to varied environments.

    PubMed

    Napier, Joseph D; Mordecai, Erin A; Heckman, Robert W

    2016-06-01

    By altering the strength of intra- and interspecific competition, droughts may reshape plant communities. Furthermore, species may respond differently to drought when other influences, such as herbivory, are considered. To explore this relationship, we conducted a greenhouse experiment measuring responses to inter- and intraspecific competition for two grasses, Schedonorus arundinaceus and Paspalum dilatatum, while varying water availability and simulating herbivory via clipping. We then parameterized population growth models to examine the long-term outcome of competition under these conditions. Under drought, S. arundinaceus was less water stressed than P. dilatatum, which exhibited severe water stress; clipping alleviated this stress, increasing the competitive ability of P. dilatatum relative to S. arundinaceus. Although P. dilatatum competed weakly under drought, clipping reduced water stress in P. dilatatum, thereby enhancing its ability to compete with S. arundinaceus under drought. Supporting these observations, population growth models predicted that P. dilatatum would exclude S. arundinaceus when clipped under drought, while S. arundinaceus would exclude P. dilatatum when unclipped under drought. When the modeled environment varied temporally, environmental variation promoted niche differences that, though insufficient to maintain stable coexistence, prevented unconditional competitive exclusion by promoting priority effects. Our results suggest that it is important to consider how species respond not just to stable, but also to variable, environments. When species differ in their responses to drought, competition, and simulated herbivory, stable environments may promote competitive exclusion, while fluctuating environments may promote coexistence. These interactions are critical to understanding how species will respond to global change.

  5. Competition between near and far dispersers in spatially structured habitats.

    PubMed

    Hiebeler, David

    2004-11-01

    Competitive interactions and invasibility between short- and long-distance dispersal was investigated in a population on a heterogeneous landscape with spatial correlations in habitat types, and where the driving interaction between individuals is competition for space. Stochastic spatially explicit simulations were used, along with differential equation models based on pair approximations. Conditions under which either dispersal strategy can successfully invade the other were determined, as a function of the amount and clustering of suitable habitat and the relative costs involved in the two dispersal strategies. Long-distance dispersal, which reduces intraspecific competition, is sometimes advantageous even where aggregation of suitable habitat would otherwise favor short-distance dispersal, although certain habitat distributions can lead to either strategy being dominant. Coexistence is also possible on some landscapes, where the spatial structure of the populations partitions suitable sites according to the number of suitable neighboring sites. Mutual competitive exclusion, where whichever strategy is established first cannot be invaded, is also possible. All of these results are observed even when there is no intrinsic difference in the two strategies' costs, such as mortality or competitive abilities.

  6. 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.

  7. 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.

  8. 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. PMID:25314476

  9. 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.

  10. Spatial patterns, ecological niches, and interspecific competition of avian brood parasites: inferring from a case study of Korea.

    PubMed

    Lee, Jin-Won; Noh, Hee-Jin; Lee, Yunkyoung; Kwon, Young-Soo; Kim, Chang-Hoe; Yoo, Jeong-Chil

    2014-09-01

    Since obligate avian brood parasites depend completely on the effort of other host species for rearing their progeny, the availability of hosts will be a critical resource for their life history. Circumstantial evidence suggests that intense competition for host species may exist not only within but also between species. So far, however, few studies have demonstrated whether the interspecific competition really occurs in the system of avian brood parasitism and how the nature of brood parasitism is related to their niche evolution. Using the occurrence data of five avian brood parasites from two sources of nationwide bird surveys in South Korea and publically available environmental/climatic data, we identified their distribution patterns and ecological niches, and applied species distribution modeling to infer the effect of interspecific competition on their spatial distribution. We found that the distribution patterns of five avian brood parasites could be characterized by altitude and climatic conditions, but overall their spatial ranges and ecological niches extensively overlapped with each other. We also found that the predicted distribution areas of each species were generally comparable to the realized distribution areas, and the numbers of individuals in areas where multiple species were predicted to coexist showed positive relationships among species. In conclusion, despite following different coevolutionary trajectories to adapt to their respect host species, five species of avian brood parasites breeding in South Korea occupied broadly similar ecological niches, implying that they tend to conserve ancestral preferences for ecological conditions. Furthermore, our results indicated that contrary to expectation interspecific competition for host availability between avian brood parasites seemed to be trivial, and thus, play little role in shaping their spatial distributions and ecological niches. Future studies, including the complete ranges of avian brood

  11. Anesthesiology and competitive strategy.

    PubMed

    Gross, Wendy L; Gold, Barbara

    2009-03-01

    Whether we like it or not, medicine is big business. The argument is sometimes made that standard management strategies from the business world do not apply to medicine because the economics and practice of medicine are unique--driven by science and rapid rates of change. But an exploding knowledge base, light-speed technological development, and ever-changing reimbursement schemes are not exclusive to medicine and health care. Some fundamental principles of finance, business management, and strategic development have evolved to deal with problems of rapid change. These principles do apply to modern medicine. The business side of anesthesia practice is off-putting to many clinicians. However, knowledge of the market forces at play can help enhance patient care, improve service, expand opportunities, and extend the perimeter of the discipline. The mission and current market position of anesthesiology practice are considered here. PMID:19361778

  12. Controls over native perennial grass exclusion and persistence in California grasslands invaded by annuals.

    PubMed

    Mordecai, Erin A; Molinari, Nicole A; Stahlheber, Karen A; Gross, Kevin; D'Antonio, Carla

    2015-10-01

    Despite obvious impacts of nonnative species in many ecosystems, the long-term outcome of competition between native and exotic species often remains unclear. Demographic models can resolve the outcome of competition between native and exotic species and provide insight into conditions favoring exclusion vs. coexistence. California grasslands are one of the most heavily invaded ecosystems in North America. Although California native perennial bunchgrasses are thought to be restricted to a fraction of their original abundance, the eventual outcome of competition with invasive European annual grasses at a local scale (competitive exclusion, stable persistence, or priority effects) remains unresolved. Here, we used a two-species discrete time population growth model to predict the outcome of competition between exotic annual and native perennial grasses in California, and to determine the demographic traits responsible for the outcome. The model is parameterized with empirical data from several field experiments. We found that, once introduced, annual grasses persist stably with little uncertainty. Although perennial grasses are competitively excluded on average, the most likely range of model predictions also includes stable coexistence with annual grasses. As for many other perennial plants, native bunchgrass population growth is highly sensitive to the survival of adults. Management interventions that improve perennial adult survival are likely to be more effective than those that reduce exotic annual seed production or establishment, reduce competition, or increase perennial seedling establishment. Further empirical data on summer survival of bunchgrass adults and competitive effects of annuals on perennials would most improve model predictions because they contribute most to the uncertainty in the predicted outcome for the perennial grass. This work demonstrates how demographic approaches can clarify the outcome of competition between native and exotic species

  13. Controls over native perennial grass exclusion and persistence in California grasslands invaded by annuals.

    PubMed

    Mordecai, Erin A; Molinari, Nicole A; Stahlheber, Karen A; Gross, Kevin; D'Antonio, Carla

    2015-10-01

    Despite obvious impacts of nonnative species in many ecosystems, the long-term outcome of competition between native and exotic species often remains unclear. Demographic models can resolve the outcome of competition between native and exotic species and provide insight into conditions favoring exclusion vs. coexistence. California grasslands are one of the most heavily invaded ecosystems in North America. Although California native perennial bunchgrasses are thought to be restricted to a fraction of their original abundance, the eventual outcome of competition with invasive European annual grasses at a local scale (competitive exclusion, stable persistence, or priority effects) remains unresolved. Here, we used a two-species discrete time population growth model to predict the outcome of competition between exotic annual and native perennial grasses in California, and to determine the demographic traits responsible for the outcome. The model is parameterized with empirical data from several field experiments. We found that, once introduced, annual grasses persist stably with little uncertainty. Although perennial grasses are competitively excluded on average, the most likely range of model predictions also includes stable coexistence with annual grasses. As for many other perennial plants, native bunchgrass population growth is highly sensitive to the survival of adults. Management interventions that improve perennial adult survival are likely to be more effective than those that reduce exotic annual seed production or establishment, reduce competition, or increase perennial seedling establishment. Further empirical data on summer survival of bunchgrass adults and competitive effects of annuals on perennials would most improve model predictions because they contribute most to the uncertainty in the predicted outcome for the perennial grass. This work demonstrates how demographic approaches can clarify the outcome of competition between native and exotic species

  14. Conclusive exclusion of quantum states

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Somshubhro; Jain, Rahul; Oppenheim, Jonathan; Perry, Christopher

    2014-02-01

    In the task of quantum state exclusion, we consider a quantum system prepared in a state chosen from a known set. The aim is to perform a measurement on the system which can conclusively rule that a subset of the possible preparation procedures cannot have taken place. We ask what conditions the set of states must obey in order for this to be possible and how well we can complete the task when it is not. The task of quantum state discrimination forms a subclass of this set of problems. Within this paper, we formulate the general problem as a semidefinite program (SDP), enabling us to derive sufficient and necessary conditions for a measurement to be optimal. Furthermore, we obtain a necessary condition on the set of states for exclusion to be achievable with certainty, and we give a construction for a lower bound on the probability of error. This task of conclusively excluding states has gained importance in the context of the foundations of quantum mechanics due to a result from Pusey, Barrett, and Rudolph (PBR). Motivated by this, we use our SDP to derive a bound on how well a class of hidden variable models can perform at a particular task, proving an analog of Tsirelson's bound for the PBR experiment and the optimality of a measurement given by PBR in the process. We also introduce variations of conclusive exclusion, including unambiguous state exclusion, and state exclusion with worst-case error.

  15. 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

  16. More competitive silicon smelting

    SciTech Connect

    Valenti, M.

    1996-02-01

    Over the past several years, foreign manufacturers of ferrosilicon and silicon alloys have been making inroads in American markets such as computer chips. To make domestic smelting of these materials more competitive, the US Department of Energy (DOE) has funded the development of a direct-current plasma-arc-furnace smelting process by the South Carolina Research Authority (SCRA) in North Charleston. This new technology can reduce the energy consumption of the smelting process, saving million of dollars in energy costs per year. Typically, silicon and ferrosilicon alloys are produced in open-top, submerged-arc, alternating-current furnaces. A mixture of quartz ore and reducing agents are fed into the furnace, multiple electrodes are inserted into the material, and the mixture is charged to produce the desired metal. The process consumes high amounts of electrical power relative to the amount of metal recovered.

  17. Mapping your competitive position.

    PubMed

    D'Aveni, Richard A

    2007-11-01

    A price-benefit positioning map helps you see, through your customers' eyes, how your product compares with all its competitors in a market. You can draw such a map quickly and objectively, without having to resort to costly, time-consuming consumer surveys or subjective estimates of the excellence of your product and the shortcomings of all the others. Creating a positioning map involves three steps: First, define your market to include everything your customers might consider to be your product's competitors or substitutes. Second, track the price your customers actually pay (wholesale or retail? bundled or unbundled?) and identify what your customers see as your offering's primary benefit. This is done through regression analysis, determining which of the product's attributes (as described objectively by rating services, government agencies, R&D departments, and the like) explains most of the variance in its price. Third, draw the map by plotting on a graph the position of every product in the market you've selected according to its price and its level of primary benefit, and draw a line that runs through the middle of the points. What you get is a picture of the competitive landscape of your market, where all the products above the line command a price premium owing to some secondary benefit customers value, and all those below the line are positioned to earn market share through lower prices and reduced secondary benefits. Using examples as varied as Harley-Davidson motorcycles, Motorola cell phones, and the New York restaurant market, Tuck professor D'Aveni demonstrates some of the many ways the maps can be used: to locate unoccupied or less-crowded spaces in highly competitive markets, for instance, or to identify opportunities created through changes in the relationship between the primary benefit and prices. The maps even allow companies to anticipate--and counter-- rivals' strategies. R eprint RO711G PMID:18159791

  18. Mapping your competitive position.

    PubMed

    D'Aveni, Richard A

    2007-11-01

    A price-benefit positioning map helps you see, through your customers' eyes, how your product compares with all its competitors in a market. You can draw such a map quickly and objectively, without having to resort to costly, time-consuming consumer surveys or subjective estimates of the excellence of your product and the shortcomings of all the others. Creating a positioning map involves three steps: First, define your market to include everything your customers might consider to be your product's competitors or substitutes. Second, track the price your customers actually pay (wholesale or retail? bundled or unbundled?) and identify what your customers see as your offering's primary benefit. This is done through regression analysis, determining which of the product's attributes (as described objectively by rating services, government agencies, R&D departments, and the like) explains most of the variance in its price. Third, draw the map by plotting on a graph the position of every product in the market you've selected according to its price and its level of primary benefit, and draw a line that runs through the middle of the points. What you get is a picture of the competitive landscape of your market, where all the products above the line command a price premium owing to some secondary benefit customers value, and all those below the line are positioned to earn market share through lower prices and reduced secondary benefits. Using examples as varied as Harley-Davidson motorcycles, Motorola cell phones, and the New York restaurant market, Tuck professor D'Aveni demonstrates some of the many ways the maps can be used: to locate unoccupied or less-crowded spaces in highly competitive markets, for instance, or to identify opportunities created through changes in the relationship between the primary benefit and prices. The maps even allow companies to anticipate--and counter-- rivals' strategies. R eprint RO711G

  19. Immunological impact of Taekwondo competitions.

    PubMed

    Lee, Y W; Shin, K W; Paik, I-Y; Jung, W M; Cho, S-Y; Choi, S T; Kim, H D; Kim, J Y

    2012-01-01

    Immunological changes in elite adolescent female athletes during Taekwondo competitions were investigated on-field. 6 female athletes (16.7 ± 0.8 year-old) volunteered and performed 5 bouts of demonstration Taekwondo competitions simulating real tournaments in intensity, duration, and break-time intervals on the same day. Blood samples were taken before, after the competitions and during the recovery, respectively. Immunological changes and oxidative stress in peripheral blood mononuclear cells were evaluated by flow-cytometry. During the competitions, exercise intensity was 92.2 ± 3.8% (86.1~95.7) of the maximal heart rate. Blood lactate increased immediately after the competitions (p=0.0165) and decreased to baseline during recovery. Intracellular reactive oxygen species (ROS) in the peripheral blood increased continuously during recovery (p<0.05, respectively). Natural killer cells increased immediately after the competitions (p=0.0006), and decreased during recovery. B and T cells increased immediately after the competitions and remained elevated throughout recovery (p<0.05, respectively). CD4/CD8 ratio after the competitions was decreased (p=0.0091) and returned to baseline during recovery. These results suggest that the immunological function of the elite female adolescent athletes could be attenuated after Taekwondo competitions. Further large-scaled Taekwondo studies on immunologic and apoptotic changes related to oxidative stress should be performed for improving and protecting the health of adolescent athletes.

  20. Spatial Aspects of Interspecific Competition

    NASA Technical Reports Server (NTRS)

    Durrett, Rick; Levin, Simon

    1998-01-01

    Using several variants of a stochastic spatial model introduced by Silvertown et al., we investigate the effect of spatial distribution of individuals on the outcome of competition. First, we prove rigorously that if one species has a competitive advantage over each of the others, then eventually it takes over all the sites in the system. Second, we examine tradeoffs between competition and dispersal distance in a two-species system. Third, we consider a cyclic competitive relationship between three types. In this case, a nonspatial treatment leads to densities that follow neutrally stable cycles or even unstable spiral solutions, while a spatial model yields a stationary distribution with an interesting spatial structure.

  1. Competitive sports for the disabled.

    PubMed

    Clark, M W

    1980-01-01

    A full life experience for people with and without physical disabilities usually includes some form of recreation or sport. Competition adds to enjoyment of sport for many people and can improve morale. This paper reviews some of the competitive opportunities available for people with a physical disability. These include competition within existing "able-bodied" organizations with or without adaptive devices and competition in separate organizations for those with disabilities. The latter include the National Wheelchair Basketball Association and the National Wheelchair Athletic Association.

  2. Gender differences in competitive stress.

    PubMed

    Madden, C C; Kirkby, R J

    1995-06-01

    Stress experienced in competitive basketball was investigated in a sample of 84 men and 49 women recruited from players engaged in regular, organized, competitive grade basketball. Subjects were administered the Stressful Situations in Basketball Questionnaire which provides measures on 5 types of stress in competitive basketball. Analyses of gender differences showed that men reported more stress than female players on the "Team performance" scale. Research is required to evaluate whether this difference is due to a perception of women that they have less influence over the performance of the team or whether it is due to men having a higher stake in the results of competition.

  3. Frequency-dependence stabilizes competitive interactions among four annual plants.

    PubMed

    Harpole, W Stanley; Suding, Katharine N

    2007-12-01

    It is the combination of large fitness differences and strong stabilizing mechanisms that often constitute niche-based explanations for species abundance patterns. Despite the importance of this assumption to much of community ecology, empirical evidence is surprisingly limited. Empirical tests are critical because many abundance patterns are also consistent with neutral-based alternatives (that assume no fitness differences or stabilization). We quantified interactions of four annual grassland species in two-species mixtures at varying frequencies. We found evidence of strong negative frequency-dependent stabilization, where scaled population growth rates increased with decreasing frequency for all four species. There was also a consistent competitive hierarchy among these species indicative of strong fitness differences that, in most cases, suggested potential competitive exclusion despite the observed strong stabilization.

  4. Student Advertising Competitions: Student Perspectives on the AAF Competition.

    ERIC Educational Resources Information Center

    Marra, James L.; Avery, James R.

    An exploratory study examined student perspectives and beliefs about involvement in the American Advertising Federation's (AAF) National Student Advertising Competition. Subjects, 34 students from 7 of the 15 winning regional teams in the 1991 AAF competition, completed a single-page, 2-part questionnaire. Multiple correlations were run on…

  5. Co-evolutionary dynamics of the bacteria Vibrio sp. CV1 and phages V1G, V1P1, and V1P2: implications for phage therapy.

    PubMed

    Barbosa, Camilo; Venail, Patrick; Holguin, Angela V; Vives, Martha J

    2013-11-01

    Bacterial infections are the second largest cause of mortality in shrimp hatcheries. Among them, bacteria from the genus Vibrio constitute a major threat. As the use of antibiotics may be ineffective and banned from the food sector, alternatives are required. Historically, phage therapy, which is the use of bacteriophages, is thought to be a promising option to fight against bacterial infections. However, as for antibiotics, resistance can be rapidly developed. Since the emergence of resistance is highly undesirable, a formal characterization of the dynamics of its acquisition is mandatory. Here, we explored the co-evolutionary dynamics of resistance between the bacteria Vibrio sp. CV1 and the phages V1G, V1P1, and V1P2. Single-phage treatments as well as a cocktail composed of the three phages were considered. We found that in the presence of a single phage, bacteria rapidly evolved resistance, and the phages decreased their infectivity, suggesting that monotherapy may be an inefficient treatment to fight against Vibrio infections in shrimp hatcheries. On the contrary, the use of a phage cocktail considerably delayed the evolution of resistance and sustained phage infectivity for periods in which shrimp larvae are most susceptible to bacterial infections, suggesting the simultaneous use of multiple phages as a serious strategy for the control of vibriosis. These findings are very promising in terms of their consequences to different industrial and medical scenarios where bacterial infections are present. PMID:24013213

  6. 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

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF DEFENSE Department of the Army Notice of Intent To Grant an Exclusive, Partially Exclusive or Non-Exclusive License of the United States Patent Application No. 13/ 543,217 Filed July 06, 2012 Entitled ''Tie-Down...

  7. 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...

  8. 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...

  9. 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....

  10. 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.

  11. 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…

  12. Balancing sexual selection through opposing mate choice and male competition

    PubMed Central

    Moore, A. J.; Moore, P. J.

    1999-01-01

    Male–male competition and female mate choice act contemporaneously in the cockroach Nauphoeta cinerea and the social pheromone of males influences the outcome of both forms of sexual selection. We therefore examined the joint and separate effects of male–male competition and female mate choice to determine if the selective optima for the pheromone were the same or different. Dominant males in a newly established hierarchy mated more frequently, but not exclusively. Manipulations of the multi-component social pheromone produced by males of N. cinerea showed that both long- and close-range attraction of females by males were influenced by the quantity and composition of the pheromone. The most attractive composition, however, differed from that which was most likely to confer high status to males. Since the outcome of male–male competition can conflict with mating preferences exhibited by females, there is balancing sexual selection on the social pheromone of N. cinerea. Such balancing selection might act to maintain genetic variation in sexually selected traits. We suggest that the different forms of sexual selection conflict in N. cinerea because females prefer a blend different to that which is most effective in male–male competition in order to avoid mating with overly aggressive males.

  13. The 2005 Australian Informatics Competition

    ERIC Educational Resources Information Center

    Clark, David

    2006-01-01

    This article describes the Australian Informatics Competition (AIC), a non-programming competition aimed at identifying students with potential in programming and algorithmic design. It is the first step in identifying students to represent Australia at the International Olympiad in Informatics. The main aim of the AIC is to increase awareness of…

  14. Fresno County Mock Trial Competition.

    ERIC Educational Resources Information Center

    Fresno City Unified School District, CA.

    THE FOLLOWING IS THE FULL TEXT OF THIS DOCUMENT: The Fresno County Office of Education and the Fresno Unified School District hosted the Mock Trial Competition. The state competition is sponsored by the Constitutional Rights Foundation, with cosponsorship from the California State Bar Association and the California Young Lawyer's Association. This…

  15. Neurocognitive Performance: Returning to Competition

    ERIC Educational Resources Information Center

    McDaniel, Larry W.; McIntire, Kyle

    2010-01-01

    Athletes who suffer from concussions under report their symptoms in order to expedite their return to competition. Athletic trainers and coaches must be aware of what is going on with athletes, even if it means requiring them to refrain from competition. Ninety percent of concussions are minor and can be difficult to diagnosis. There is a lack of…

  16. An Approach to Competitive Assessment.

    ERIC Educational Resources Information Center

    Green, Petrina M.

    1994-01-01

    Offers a detailed discussion of competitive assessment, an efficient and cost-effective method to evaluate competitive products. Describes its three phases: numerical scoring, building a best-of-breed model, and determining the gap between the best-of-breed model and another product. (SR)

  17. Competitive Electricity Prices: An Update

    EIA Publications

    1998-01-01

    Illustrates a third impact of the move to competitive generation pricing -- the narrowing of the range of prices across regions of the country. This feature article updates information in Electricity Prices in a Competitive Environment: Marginal Cost Pricing of Generation Services and Financial Status of Electric Utilities.

  18. Higher Education, Employability and Competitiveness

    ERIC Educational Resources Information Center

    Pavlin, Samo; Svetlicic, Marjan

    2012-01-01

    This paper studies the relationship between competitiveness and higher education systems in Europe. It explores whether more competitive countries have developed more labour-market-oriented systems of higher education (HE) that thereby give their graduates greater short term employability potential. Based on and a large-scale survey among 45.000…

  19. Competitive strategy a new era.

    PubMed

    Zuckerman, Alan M

    2007-11-01

    By adopting five basic practices, your organization will be ready to advance to the next level of competitive fitness: Develop a reliable financial baseline. Insist on development of a competitive intelligence database system. Employ rigorous business planning. Advocate for focus and discipline. Really commit to competing.

  20. Feature Discovery by Competitive Learning.

    ERIC Educational Resources Information Center

    Rumelhart, David E.; Zipser, David

    1985-01-01

    Reports results of studies with an unsupervised learning paradigm called competitive learning which is examined using computer simulation and formal analysis. When competitive learning is applied to parallel networks of neuron-like elements, many potentially useful learning tasks can be accomplished. (Author)

  1. DOE Collegiate Wind Competition (Presentation)

    SciTech Connect

    Jones, J.

    2014-02-01

    This presentation for the January Stakeholder Engagement and Outreach webinar outlines the expanded need for workers in the wind industry and provides an overview of the DOE Wind Competition (to be held in May 2014) and the guiding principles of the competition.

  2. Competitive Skills Project. Final Report.

    ERIC Educational Resources Information Center

    El Camino Coll., Torrance, CA.

    Almost 180 (22.5 percent) of BP Chemicals/HITCO, Inc. (BPCHI) employees have participated in the basic skills courses offered through the Competitive Skills Project (CSP) at El Camino College (Torrance, California). Workplace basics provide a solid foundation for Total Quality Management (TQM), enabling workers to be globally competitive. Two main…

  3. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Exemptions and Exclusions § 551.214 Statutory exclusion. A....S.C. 267 and under 19 CFR 24.16 for time worked may not receive pay or other compensation for...

  4. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Exemptions and Exclusions § 551.214 Statutory exclusion. A....S.C. 267 and under 19 CFR 24.16 for time worked may not receive pay or other compensation for...

  5. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Exemptions and Exclusions § 551.214 Statutory exclusion. A....S.C. 267 and under 19 CFR 24.16 for time worked may not receive pay or other compensation for...

  6. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Exemptions and Exclusions § 551.214 Statutory exclusion. A....S.C. 267 and under 19 CFR 24.16 for time worked may not receive pay or other compensation for...

  7. 5 CFR 551.214 - Statutory exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... ADMINISTRATION UNDER THE FAIR LABOR STANDARDS ACT Exemptions and Exclusions § 551.214 Statutory exclusion. A....S.C. 267 and under 19 CFR 24.16 for time worked may not receive pay or other compensation for...

  8. How competition affects evolutionary rescue

    PubMed Central

    Osmond, Matthew Miles; de Mazancourt, Claire

    2013-01-01

    Populations facing novel environments can persist by adapting. In nature, the ability to adapt and persist will depend on interactions between coexisting individuals. Here we use an adaptive dynamic model to assess how the potential for evolutionary rescue is affected by intra- and interspecific competition. Intraspecific competition (negative density-dependence) lowers abundance, which decreases the supply rate of beneficial mutations, hindering evolutionary rescue. On the other hand, interspecific competition can aid evolutionary rescue when it speeds adaptation by increasing the strength of selection. Our results clarify this point and give an additional requirement: competition must increase selection pressure enough to overcome the negative effect of reduced abundance. We therefore expect evolutionary rescue to be most likely in communities which facilitate rapid niche displacement. Our model, which aligns to previous quantitative and population genetic models in the absence of competition, provides a first analysis of when competitors should help or hinder evolutionary rescue. PMID:23209167

  9. Competition among leukemic cells.

    PubMed

    Aflalo, E; Weinstein, Y

    1990-01-01

    We investigated competition among leukemic cells induced by Moloney murine leukemia virus (MoLV) in order to understand the mechanisms involved in the generation of leukemia. We used six leukemic cells lines from Balb/C mice infected with MoLV. Each line had a unique genetic marker which enabled us to trace it in mixtures of cells either in vivo or in vitro. The markers were a unique rearrangement of T-cell receptors, the integration sites of the retrovirus and rearrangements in the Pim-1 oncogene. A mixture of two cell lines (1:1) injected into intact Balb/C mice usually produced a monoclonal tumor originating from one cell line. In most cases, the cell lines that were aggressive in vivo were also dominant in mixing experiments in vitro. In some lines, we could correlate the aggressiveness of the tumor to its superior growth rate and lower requirement for serum factors in vitro. In others, this correlation did not hold, and we assumed that host factors like the immune system contribute to the malignant potential of the leukemic cell.

  10. Mechanics of competition walking.

    PubMed

    Cavagna, G A; Franzetti, P

    1981-06-01

    1. The work done at each step to lift and accelerate the centre of mass of the body has been measured in competition walkers during locomotion from 2 to 20 km/hr. 2. Three distinct phases characterize the mechanics of walking. From 2 to 6 km/hr the vertical displacement during each step, Sv, increases to a maximum (3.5 vs. 6 cm in normal walking) due to an increase in the amplitude of the rotation over the supporting leg. 3. The transfer, R, between potential energy of vertical displacement and kinetic energy of forward motion during this rotation, reaches a maximum at 4-5 km/hr (R = 65%). From 6 to 10 km/hr R decreases more steeply than in normal walking, indicating a smaller utilization of the pendulum-like mechanism characteristic of walking. 4. Above 10 km/hr potential and kinetic energies vary during each step because both are simultaneously taken up and released by the muscles with almost no transfer between them (R = 2-10%). Above 13-14 km/hr an aerial phase (25-60 msec) takes place during the step. 5. Speeds considerably greater than in normal walking are attained thanks to a greater efficiency of doing positive work. This is made possible by a mechanism of locomotion allowing an important storage and recovery of mechanical energy by the muscles.

  11. Female competition in chimpanzees.

    PubMed

    Pusey, Anne E; Schroepfer-Walker, Kara

    2013-01-01

    Female chimpanzees exhibit exceptionally slow rates of reproduction and raise their offspring without direct paternal care. Therefore, their reproductive success depends critically on long-term access to high-quality food resources over a long lifespan. Chimpanzee communities contain multiple adult males, multiple adult females and their offspring. Because males are philopatric and jointly defend the community range while most females transfer to new communities before breeding, adult females are typically surrounded by unrelated competitors. Communities are fission-fusion societies in which individuals spend time alone or in fluid subgroups, whose size depends mostly on the abundance and distribution of food. To varying extents in different populations, females avoid direct competition by foraging alone or in small groups in distinct, but overlapping core areas within the community range to which they show high fidelity. Although rates of aggression are low, females compete for space and access to food. High rank correlates with high reproductive success, and high-ranking females win direct contests for food and gain preferential access to resource-rich sites. Females are aggressive to immigrant females and even kill the newborn infants of community members. The intensity of such aggression correlates with population density. These patterns are compared to those in other species, including humans.

  12. Advances and trends in the molecular systematics of anisakid nematodes, with implications for their evolutionary ecology and host-parasite co-evolutionary processes.

    PubMed

    Mattiucci, Simonetta; Nascetti, Giuseppe

    2008-01-01

    The application of molecular systematics to the anisakid nematodes of the genera Anisakis, Pseudoterranova and Contracaecum, parasites of aquatic organisms, over the last two decades, has advanced the understanding of their systematics, taxonomy, ecology and phylogeny substantially. Here the results of this effort on this group of species from the early genetic works to the current status of their revised taxonomy, ecology and evolutionary aspects are reviewed for each of three parasitic groups. It has been shown that many anisakid morphospecies of Anisakis, Contracaecum and Pseudoterranova include a certain number of sibling species. Molecular genetic markers provided a rapid, precise means to screen and identify several species that serve as definitive and intermediate and or/paratenic hosts of the so far genetically characterized species. Patterns of differential distribution of anisakid nematodes in various definitive and intermediate hosts are presented. Differences in the life history of related species can be due both to differential host-parasite co-adaptation and co-evolution, and/or to interspecific competition, that can reduce the range of potential hosts in sympatric conditions. Phylogenetic hypotheses attempted for anisakid nematodes and the possible evolutionary scenarios that have been proposed inferred from molecular data, also with respect to the phylogeny of their hosts are presented for the parasite-host associations Anisakis-cetaceans and Contracaecum-pinnipeds, showing that codivergence and host-switching events could have accompanied the evolution of these groups of parasites. Finally, examples in which anisakid nematodes recognized genetically at the species level in definitive and intermediate/paratenic hosts from various geographical areas of the Boreal and Austral regions and their infection levels have been used as biological indicators of fish stocks and food-web integrity in areas at high versus low levels of habitat disturbance

  13. 40 CFR 122.3 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 22 2014-07-01 2013-07-01 true Exclusions. 122.3 Section 122.3... § 122.3 Exclusions. The following discharges do not require NPDES permits: (a) Any discharge of sewage... wastes, or any other discharge incidental to the normal operation of a vessel. This exclusion does...

  14. 5 CFR 351.402 - Competitive area.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Competitive area. 351.402 Section 351.402... Competition § 351.402 Competitive area. (a) Each agency shall establish competitive areas in which employees compete for retention under this part. (b) A competitive area must be defined solely in terms of...

  15. 5 CFR 351.402 - Competitive area.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 1 2013-01-01 2013-01-01 false Competitive area. 351.402 Section 351.402... Competition § 351.402 Competitive area. (a) Each agency shall establish competitive areas in which employees compete for retention under this part. (b) A competitive area must be defined solely in terms of...

  16. 5 CFR 351.402 - Competitive area.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 1 2012-01-01 2012-01-01 false Competitive area. 351.402 Section 351.402... Competition § 351.402 Competitive area. (a) Each agency shall establish competitive areas in which employees compete for retention under this part. (b) A competitive area must be defined solely in terms of...

  17. 5 CFR 351.402 - Competitive area.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Competitive area. 351.402 Section 351.402... Competition § 351.402 Competitive area. (a) Each agency shall establish competitive areas in which employees compete for retention under this part. (b) A competitive area must be defined solely in terms of...

  18. 5 CFR 351.403 - Competitive level.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Competitive level. 351.403 Section 351... FORCE Scope of Competition § 351.403 Competitive level. (a)(1) Each agency shall establish competitive levels consisting of all positions in a competitive area which are in the same grade (or...

  19. 5 CFR 351.403 - Competitive level.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Competitive level. 351.403 Section 351... FORCE Scope of Competition § 351.403 Competitive level. (a)(1) Each agency shall establish competitive levels consisting of all positions in a competitive area which are in the same grade (or...

  20. Sperm competition and ejaculate economics.

    PubMed

    Parker, Geoff A; Pizzari, Tommaso

    2010-11-01

    Sperm competition was identified in 1970 as a pervasive selective force in post-copulatory sexual selection that occurs when the ejaculates of different males compete to fertilise a given set of ova. Since then, sperm competition has been much studied both empirically and theoretically. Because sperm competition often favours large ejaculates, an important challenge has been to understand the evolution of strategies through which males invest in sperm production and economise sperm allocation to maximise reproductive success under competitive conditions. Sperm competition mechanisms vary greatly, depending on many factors including the level of sperm competition, space constraints in the sperm competition arena, male mating roles, and female influences on sperm utilisation. Consequently, theoretical models of ejaculate economics are complex and varied, often with apparently conflicting predictions. The goal of this review is to synthesise the theoretical basis of ejaculate economics under sperm competition, aiming to provide empiricists with categorised model assumptions and predictions. We show that apparent contradictions between older and newer models can often be reconciled and there is considerable consensus in the predictions generated by different models. We also discuss qualitative empirical support for some of these predictions, and detail quantitative matches between predictions and observations that exist in the yellow dung fly. We argue that ejaculate economic theory represents a powerful heuristic to explain the diversity in ejaculate traits at multiple levels: across species, across males and within individual males. Future progress requires greater understanding of sperm competition mechanisms, quantification of trade-offs between ejaculate allocation and numbers of matings gained, further knowledge of mechanisms of female sperm selection and their associated costs, further investigation of non-sperm ejaculate effects, and theoretical integration of

  1. Testosterone, cortisol, and human competition.

    PubMed

    Casto, Kathleen V; Edwards, David A

    2016-06-01

    Testosterone and cortisol figure prominently in the research literature having to do with human competition. In this review, we track the history of this literature, concentrating particularly on major theoretical and empirical contributions, and provide commentary on what we see as important unresolved issues. In men and women, athletic competition is typically associated with an increase in testosterone (T) and cortisol (C). Hormone changes in response to non-athletic competition are less predictable. Person (e.g., power motivation, mood, aggressiveness, social anxiety, sex, and baseline levels of T and C) and context (e.g., whether a competition is won or lost, the closeness of the competition, whether the outcome is perceived as being influenced by ability vs. chance, provocations) factors can influence hormone responses to competition. From early on, studies pointed to a positive relationship between T and dominance motivation/status striving. Recent research, however, suggests that this relationship only holds for individuals with low levels of C - this is the core idea of the dual-hormone hypothesis, and it is certain that the broadest applications of the hypothesis have not yet been realized. Individuals differ with respect to the extent to which they embrace competition, but the hormonal correlates of competitiveness remain largely unexplored. Although rapid increases in both T and C associated with competition are likely adaptive, we still know very little about the psychological benefits of these hormonal changes. Administration studies have and will continue to contribute to this inquiry. We close with a discussion of what, we think, are important methodological and mechanistic issues for future research.

  2. Testosterone, cortisol, and human competition.

    PubMed

    Casto, Kathleen V; Edwards, David A

    2016-06-01

    Testosterone and cortisol figure prominently in the research literature having to do with human competition. In this review, we track the history of this literature, concentrating particularly on major theoretical and empirical contributions, and provide commentary on what we see as important unresolved issues. In men and women, athletic competition is typically associated with an increase in testosterone (T) and cortisol (C). Hormone changes in response to non-athletic competition are less predictable. Person (e.g., power motivation, mood, aggressiveness, social anxiety, sex, and baseline levels of T and C) and context (e.g., whether a competition is won or lost, the closeness of the competition, whether the outcome is perceived as being influenced by ability vs. chance, provocations) factors can influence hormone responses to competition. From early on, studies pointed to a positive relationship between T and dominance motivation/status striving. Recent research, however, suggests that this relationship only holds for individuals with low levels of C - this is the core idea of the dual-hormone hypothesis, and it is certain that the broadest applications of the hypothesis have not yet been realized. Individuals differ with respect to the extent to which they embrace competition, but the hormonal correlates of competitiveness remain largely unexplored. Although rapid increases in both T and C associated with competition are likely adaptive, we still know very little about the psychological benefits of these hormonal changes. Administration studies have and will continue to contribute to this inquiry. We close with a discussion of what, we think, are important methodological and mechanistic issues for future research. PMID:27103058

  3. 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.

  4. FIRST 2002, 2003, 2004 Robotics Competition(s)

    NASA Technical Reports Server (NTRS)

    Purman, Richard

    2004-01-01

    The New Horizons Regional Education Center (NHREC) in Hampton, VA sought and received NASA funding to support its participation in the 2002, 2003, and 2004 FIRST Robotics Competitions. 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.

  5. Distributional preferences and competitive behavior.

    PubMed

    Balafoutas, Loukas; Kerschbamer, Rudolf; Sutter, Matthias

    2012-06-01

    We study experimentally the relationship between distributional preferences and competitive behavior. We find that spiteful subjects react strongest to competitive pressure and win in a tournament significantly more often than efficiency-minded and inequality averse subjects. However, when given the choice between a tournament and a piece rate scheme, efficiency-minded subjects choose the tournament most often, while spiteful and inequality averse subjects avoid it. When controlling for distributional preferences, risk attitudes and past performance, the gender gap in the willingness to compete is no longer significant, indicating that gender-related variables explain why twice as many men as women self-select into competition.

  6. Gender and competitive preferences: The role of competition size.

    PubMed

    Hanek, Kathrin J; Garcia, Stephen M; Tor, Avishalom

    2016-08-01

    In a series of 8 studies, we examine whether gender differences in competition entry preferences are moderated by the size of the competition. Drawing on theories of gender roles and stereotypes, we show that women, relative to men, prefer to enter smaller compared with larger competitions. Studies 1a and 1b demonstrate this effect in observational data on preferences for working in differently sized firms and applying to differently sized colleges. Studies 2a and 2b replicate the effect with real behavioral decisions in different domains. We also find empirical evidence that prescriptive gender norms and stereotypes underlie this effect. In Study 3, we find experimental evidence that women and men differ in their preferences for differently sized groups under competition, but not in noncompetitive settings. Three additional experimental studies (Studies 4, 5a, and 5b) show that perceptions of comfort in small versus larger competitions underlie women's preferences. These findings suggest that women's preferences for smaller competitions may be driven by an adherence to prescriptive gender norms. We discuss the implications of the current findings for gender inequalities in organizations. (PsycINFO Database Record PMID:27176148

  7. [Mothers' knowledge about exclusive breastfeeding].

    PubMed

    da Silva, Nichelle Monique; Waterkemper, Roberta; da Silva, Eveline Franco; Cordova, Fernanda Peixoto; Bonilha, Ana Lucia de Lourenzi

    2014-01-01

    This is a descriptive study, with a qualitative approach, aimed to identify the knowledge of puerperal women on exclusive breastfeeding. Data were collected between September-October 2011, through semi-structured interview. Thirteen puerperal women, interned in a rooming unit of a public institution in the city of Caxias do Sul-RS, participated in the study. Data analysis was performed using thematic analysis. From the interpretation of information three categories emerged: the knowledge about exclusive breastfeeding, the breastfeeding process and the influences of received information. Even getting information from health professionals in the prenatal period, it is possible to understand that there is a need to improve communication and monitoring of mothers, as a continuity of professional care in the postpartum period, and also later, in the remote.

  8. 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

  9. Competitive hybridization models

    NASA Astrophysics Data System (ADS)

    Cherepinsky, Vera; Hashmi, Ghazala; Mishra, Bud

    2010-11-01

    Microarray technology, in its simplest form, allows one to gather abundance data for target DNA molecules, associated with genomes or gene-expressions, and relies on hybridizing the target to many short probe oligonucleotides arrayed on a surface. While for such multiplexed reactions conditions are optimized to make the most of each individual probe-target interaction, subsequent analysis of these experiments is based on the implicit assumption that a given experiment yields the same result regardless of whether it was conducted in isolation or in parallel with many others. It has been discussed in the literature that this assumption is frequently false, and its validity depends on the types of probes and their interactions with each other. We present a detailed physical model of hybridization as a means of understanding probe interactions in a multiplexed reaction. Ultimately, the model can be derived from a system of ordinary differential equations (ODE’s) describing kinetic mass action with conservation-of-mass equations completing the system. We examine pairwise probe interactions in detail and present a model of “competition” between the probes for the target—especially, when the target is effectively in short supply. These effects are shown to be predictable from the affinity constants for each of the four probe sequences involved, namely, the match and mismatch sequences for both probes. These affinity constants are calculated from the thermodynamic parameters such as the free energy of hybridization, which are in turn computed according to the nearest neighbor (NN) model for each probe and target sequence. Simulations based on the competitive hybridization model explain the observed variability in the signal of a given probe when measured in parallel with different groupings of other probes or individually. The results of the simulations can be used for experiment design and pooling strategies, based on which probes have been shown to have a strong

  10. Competitive Strategy in Continuing Education.

    ERIC Educational Resources Information Center

    Baden, Clifford

    1987-01-01

    Reviews strategic variables available to those planning continuing education marketing programs. Discusses generic competitive strategies: (1) overall cost leadership, (2) differentiation, and (3) specialization. Mentions several potential problems. (CH)

  11. Do human females use indirect aggression as an intrasexual competition strategy?

    PubMed Central

    Vaillancourt, Tracy

    2013-01-01

    Indirect aggression includes behaviours such as criticizing a competitor's appearance, spreading rumours about a person's sexual behaviour and social exclusion. Human females have a particular proclivity for using indirect aggression, which is typically directed at other females, especially attractive and sexually available females, in the context of intrasexual competition for mates. Indirect aggression is an effective intrasexual competition strategy. It is associated with a diminished willingness to compete on the part of victims and with greater dating and sexual behaviour among those who perpetrate the aggression. PMID:24167310

  12. Competitive mechanisms change with ontogeny in coral-dwelling gobies.

    PubMed

    Pereira, Pedro H Cipresso; Munday, Philip L; Jones, Geoffrey P

    2015-11-01

    fitness loss when occupying the non-preferred coral (A. spathulata) compared with G. histrio, which could explain its ability to persist when displaced by the superior competitor. These results suggest that the competitive mechanism operating between the two Gobiodon species shifts from a lottery for space to niche partitioning through ontogeny, and that these two mechanisms of competitive coexistence are not mutually exclusive.

  13. Competitive mechanisms change with ontogeny in coral-dwelling gobies.

    PubMed

    Pereira, Pedro H Cipresso; Munday, Philip L; Jones, Geoffrey P

    2015-11-01

    fitness loss when occupying the non-preferred coral (A. spathulata) compared with G. histrio, which could explain its ability to persist when displaced by the superior competitor. These results suggest that the competitive mechanism operating between the two Gobiodon species shifts from a lottery for space to niche partitioning through ontogeny, and that these two mechanisms of competitive coexistence are not mutually exclusive. PMID:27070026

  14. An amusement park physics competition

    NASA Astrophysics Data System (ADS)

    Moll, Rachel F.

    2010-07-01

    Amusement park physics is a popular way to reinforce physics concepts and to motivate physics learners. This article describes a novel physics competition where students use simple tools to take amusement park ride measurements and use the data to answer challenging exam questions. Research into the impact of participating in the competition reveals positive effects such as the acquisition of experimentation skills and improved attitudes towards physics.

  15. Chemical defense lowers plant competitiveness.

    PubMed

    Ballhorn, Daniel J; Godschalx, Adrienne L; Smart, Savannah M; Kautz, Stefanie; Schädler, Martin

    2014-11-01

    Both plant competition and plant defense affect biodiversity and food web dynamics and are central themes in ecology research. The evolutionary pressures determining plant allocation toward defense or competition are not well understood. According to the growth-differentiation balance hypothesis (GDB), the relative importance of herbivory and competition have led to the evolution of plant allocation patterns, with herbivore pressure leading to increased differentiated tissues (defensive traits), and competition pressure leading to resource investment towards cellular division and elongation (growth-related traits). Here, we tested the GDB hypothesis by assessing the competitive response of lima bean (Phaseolus lunatus) plants with quantitatively different levels of cyanogenesis-a constitutive direct, nitrogen-based defense against herbivores. We used high (HC) and low cyanogenic (LC) genotypes in different competition treatments (intra-genotypic, inter-genotypic, interspecific), and in the presence or absence of insect herbivores (Mexican bean beetle, Epilachna varivestis) to quantify vegetative and generative plant parameters (above and belowground biomass as well as seed production). Highly defended HC-plants had significantly lower aboveground biomass and seed production than LC-plants when grown in the absence of herbivores implying significant intrinsic costs of plant cyanogenesis. However, the reduced performance of HC- compared to LC-plants was mitigated in the presence of herbivores. The two plant genotypes exhibited fundamentally different responses to various stresses (competition, herbivory). Our study supports the GDB hypothesis by demonstrating that competition and herbivory affect different plant genotypes differentially and contributes to understanding the causes of variation in defense within a single plant species.

  16. Competitive spatially distributed population dynamics models: Does diversity in diffusion strategies promote coexistence?

    PubMed

    Braverman, E; Kamrujjaman, Md; Korobenko, L

    2015-06-01

    We study the interaction between different types of dispersal, intrinsic growth rates and carrying capacities of two competing species in a heterogeneous environment: one of them is subject to a regular diffusion while the other moves in the direction of most per capita available resources. If spatially heterogeneous carrying capacities coincide, and intrinsic growth rates are proportional then competitive exclusion of a regularly diffusing population is inevitable. However, the situation may change if intrinsic growth rates for the two populations have different spatial forms. We also consider the case when carrying capacities are different. If the carrying capacity of a regularly diffusing population is higher than for the other species, the two populations may coexist; as the difference between the two carrying capacities grows, competitive exclusion of the species with a lower carrying capacity occurs.

  17. Competitive Bidding in Medicare: Who Benefits From Competition?

    PubMed Central

    Song, Zirui; Landrum, Mary Beth; Chernew, Michael E.

    2012-01-01

    Objectives To conduct the first empirical study of competitive bidding in Medicare. Study Design and Methods We analyzed 2006–2010 Medicare Advantage data from the Centers for Medicare & Medicaid Services using longitudinal models adjusted for market and plan characteristics. Results A $1 increase in Medicare's payment to health maintenance organization (HMO) plans led to a $0.49 (P <.001) increase in plan bids, with $0.34 (P <.001) going to beneficiaries in the form of extra benefits or lower cost sharing. With preferred provider organization and private fee-for-service plans included, higher Medicare payments increased bids less ($0.33 per dollar), suggesting more competition among these latter plans. Conclusions As a market-based alternative to cost control through administrative pricing, competitive bidding relies on private insurance plans proposing prices they are willing to accept for insuring a beneficiary. However, competition is imperfect in the Medicare bidding market. As much as half of every dollar in increased plan payment went to higher bids rather than to beneficiaries. While having more insurers in a market lowered bids, the design of any bidding system for Medicare should recognize this shortcoming of competition. PMID:23009305

  18. Predation, Competition, and Abiotic Disturbance: Population Dynamics of Small Mammals

    SciTech Connect

    Yunger, John A.; /Northern Illinois U. /Northern Illinois U.

    1996-01-01

    Predation and food availability have been implicated in annual non-cyclic fluctuations of vertebrate prey at mid-latitudes. The timing and magnitude of these factors are unclear due to a lack of large-scale field experiments, little attention to interactions, and a failure to closely link vertebrate predators with their prey. From October 1992 to January 1996, small mammal populations were censused on eight 0.6 ha plots at monthly intervals in a 32-ha prairie restoration at Fermi National Accelerator Laboratory, Illinois. Terrestrial vertebrate predators were excluded after July 1993 from four of the eight plots and canid diets monitored. Both terrestrial and avian vertebrate predators were excluded in March 1994. During 1993 small mammal densities (i.e., Microtus Pennsylvanicus, Peromyscus leucopus, and P. maniculatus) were relatively high. Following peak densities in late summer, Microtus numbers wer 2-3x greater on exclusion plots relative to controls due to preferential selection of Microtus by canids, as reflected in dits. Following an ice-storm and crash in small mammal numbers (particularly Microtus), vertebrate predator exclusion had no detectable effect on P. leucopus numbers, probably due to an abundance of alternative prey (i.e., Sylvilagus floridanus). Meadow vole numbers began to increase in Fall 1995, and a numerical effect of predator exclusion, similar to that in 1993, was observed. Predator exclusion had no detectable effect on the movements and spatial patterns of Microtus during 1993. There was a significant decrease in home range and a significant increase in home range overlap for P. leucopus on the predator exclusion plots. The change in spatial behavior may be due to interspecific competition with Microtus resulting from increased densities on exclusion plots. Thus, predators had an indirect effect on P. leucopus spatial patterns mediated through M. Pennsylvanicus. The role of food limitation was studied using natural and manipulative

  19. Competitive helping in online giving.

    PubMed

    Raihani, Nichola J; Smith, Sarah

    2015-05-01

    Unconditional generosity in humans is a puzzle. One possibility is that individuals benefit from being seen as generous if there is competition for access to partners and if generosity is a costly-and therefore reliable-signal of partner quality [1-3]. The "competitive helping" hypothesis predicts that people will compete to be the most generous, particularly in the presence of attractive potential partners [1]. However, this key prediction has not been directly tested. Using data from online fundraising pages, we demonstrate competitive helping in the real world. Donations to fundraising pages are public and made sequentially. Donors can therefore respond to the behavior of previous donors, creating a potential generosity tournament. Our test of the competitive helping hypothesis focuses on the response to large, visible donations. We show that male donors show significantly stronger responses (by donating more) when they are donating to an attractive female fundraiser and responding to a large donation made by another male donor. The responses for this condition are around four times greater than when males give to less-attractive female (or male) fundraisers or when they respond to a large donation made by a female donor. Unlike males, females do not compete in donations when giving to attractive male fundraisers. These data suggest that males use competitive helping displays in the presence of attractive females and suggest a role for sexual selection in explaining unconditional generosity.

  20. The Scientific Competitiveness of Nations

    PubMed Central

    Cimini, Giulio; Gabrielli, Andrea; Sylos Labini, Francesco

    2014-01-01

    We use citation data of scientific articles produced by individual nations in different scientific domains to determine the structure and efficiency of national research systems. We characterize the scientific fitness of each nation—that is, the competitiveness of its research system—and the complexity of each scientific domain by means of a non-linear iterative algorithm able to assess quantitatively the advantage of scientific diversification. We find that technological leading nations, beyond having the largest production of scientific papers and the largest number of citations, do not specialize in a few scientific domains. Rather, they diversify as much as possible their research system. On the other side, less developed nations are competitive only in scientific domains where also many other nations are present. Diversification thus represents the key element that correlates with scientific and technological competitiveness. A remarkable implication of this structure of the scientific competition is that the scientific domains playing the role of “markers” of national scientific competitiveness are those not necessarily of high technological requirements, but rather addressing the most “sophisticated” needs of the society. PMID:25493626

  1. Business Plan Competitions: An Overview. CELCEE Digest.

    ERIC Educational Resources Information Center

    Seymour, Nicole

    This document describes business plan competitions sponsored by universities. The idea began in the early 1980s at the University of Texas when Masters in Business Administration (MBA) students created a friendly competitive activity along the lines of the law schools Moot Court competition. Later the competition became national, and then…

  2. 32 CFR 22.320 - Special competitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 1 2014-07-01 2014-07-01 false Special competitions. 22.320 Section 22.320... REGULATIONS DoD GRANTS AND AGREEMENTS-AWARD AND ADMINISTRATION Competition § 22.320 Special competitions. Some... competed specifically among institutions of higher education. All such special competitions shall...

  3. 24 CFR 791.406 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Competition. 791.406 Section 791... Authority for Housing Assistance § 791.406 Competition. (a) All budget authority allocated pursuant to § 791.403(b)(2) shall be reserved and obligated pursuant to a competition. Any such competition shall...

  4. 24 CFR 791.406 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Competition. 791.406 Section 791... Authority for Housing Assistance § 791.406 Competition. (a) All budget authority allocated pursuant to § 791.403(b)(2) shall be reserved and obligated pursuant to a competition. Any such competition shall...

  5. 24 CFR 791.406 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Competition. 791.406 Section 791... Authority for Housing Assistance § 791.406 Competition. (a) All budget authority allocated pursuant to § 791.403(b)(2) shall be reserved and obligated pursuant to a competition. Any such competition shall...

  6. 24 CFR 791.406 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Competition. 791.406 Section 791... Authority for Housing Assistance § 791.406 Competition. (a) All budget authority allocated pursuant to § 791.403(b)(2) shall be reserved and obligated pursuant to a competition. Any such competition shall...

  7. 7 CFR 3430.11 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Competition. 3430.11 Section 3430.11 Agriculture... Pre-award: Solicitation and Application § 3430.11 Competition. (a) Standards for competition. Except..., unless restricted by statute, only after competition. (b) Exception. The NIFA ADO and the...

  8. 7 CFR 3430.11 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Competition. 3430.11 Section 3430.11 Agriculture... Pre-award: Solicitation and Application § 3430.11 Competition. (a) Standards for competition. Except... agreements, unless restricted by statute, only after competition. (b) Exception. The CSREES ADO and...

  9. 7 CFR 3430.11 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Competition. 3430.11 Section 3430.11 Agriculture... Pre-award: Solicitation and Application § 3430.11 Competition. (a) Standards for competition. Except..., unless restricted by statute, only after competition. (b) Exception. The NIFA ADO and the...

  10. 7 CFR 3430.11 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Competition. 3430.11 Section 3430.11 Agriculture... Pre-award: Solicitation and Application § 3430.11 Competition. (a) Standards for competition. Except..., unless restricted by statute, only after competition. (b) Exception. The NIFA ADO and the...

  11. 32 CFR 22.320 - Special competitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 1 2012-07-01 2012-07-01 false Special competitions. 22.320 Section 22.320... REGULATIONS DoD GRANTS AND AGREEMENTS-AWARD AND ADMINISTRATION Competition § 22.320 Special competitions. Some... competed specifically among institutions of higher education. All such special competitions shall...

  12. 24 CFR 791.406 - Competition.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Competition. 791.406 Section 791... Authority for Housing Assistance § 791.406 Competition. (a) All budget authority allocated pursuant to § 791.403(b)(2) shall be reserved and obligated pursuant to a competition. Any such competition shall...

  13. 48 CFR 570.203-2 - Competition.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Competition. 570.203-2... 570.203-2 Competition. (a) Solicit at least three sources to promote competition to the maximum extent..., document the file to explain the lack of competition....

  14. 78 FR 20697 - New Competitive Product

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-05

    ... is noticing a recent Postal Service filing concerning an addition to the competitive product list... 57 to the competitive product list.\\1\\ It asserts that Priority Mail Contract 57 is a competitive... Priority Mail Contract 57 to Competitive Product List and Notice of Filing (Under Seal) of...

  15. 40 CFR 35.603 - Competitive process.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Competitive process. 35.603 Section 35... (section 104(b)(3)) § 35.603 Competitive process. EPA will award water quality cooperative agreement funds through a competitive process in accordance with national program guidance. After the competitive...

  16. 40 CFR 35.382 - Competitive process.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Competitive process. 35.382 Section 35...)(3)) § 35.382 Competitive process. State Wetlands Development Grants are awarded on a competitive... established by EPA. After the competitive process is complete, the recipient can, at its discretion,...

  17. 40 CFR 35.382 - Competitive process.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Competitive process. 35.382 Section 35...)(3)) § 35.382 Competitive process. State Wetlands Development Grants are awarded on a competitive... established by EPA. After the competitive process is complete, the recipient can, at its discretion,...

  18. 40 CFR 35.382 - Competitive process.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Competitive process. 35.382 Section 35...)(3)) § 35.382 Competitive process. State Wetlands Development Grants are awarded on a competitive... established by EPA. After the competitive process is complete, the recipient can, at its discretion,...

  19. 40 CFR 35.382 - Competitive process.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Competitive process. 35.382 Section 35...)(3)) § 35.382 Competitive process. State Wetlands Development Grants are awarded on a competitive... established by EPA. After the competitive process is complete, the recipient can, at its discretion,...

  20. Competition among native and invasive Impatiens species: the roles of environmental factors, population density and life stage.

    PubMed

    Čuda, Jan; Skálová, Hana; Janovský, Zdeněk; Pyšek, Petr

    2015-04-01

    Many invasive species are considered competitively superior to native species, with the strongest competition expected in species with similar niches and/or in closely related species. However, competition outcome is strongly context-dependent as competitive strength varies along environmental gradients, and life stages, and also depends on abundances. To explore the importance of these factors, we examined competition effects in an experiment with three Impatiens species (Balsaminaceae) widespread in central Europe and sharing similar life-history characteristics and habitats: the native I. noli-tangere, and two invasive species, I. parviflora and I. glandulifera. We compared their competitive strength and reciprocal impacts under two levels of water and light availability, two overall planting densities and three competitor densities. We assessed species performance (ability to complete the life-cycle, biomass and fecundity) and temporal competition dynamics in a garden pot experiment. Environmental variables had lower explanatory power than overall planting and competitor density, which indicates the importance of competitive interactions when evaluating plant performance and potential invasion success. Despite poor and delayed germination, the invasive I. glandulifera attained dominance even at a high competitor density and was competitively superior across all treatments, exceeding the height of both congeners. Impatiens parviflora was competitively weakest, having a negligible impact on both native I. noli-tangere and invasive I. glandulifera. The intermediate competitive strength of the native I. noli-tangere probably results from its intermediate height, and good germination rate and timing. The difference in height among species increased during the experiment when I. glandulifera was involved; this species continues growing until autumn, enhancing its competitive superiority. The results provide a mechanistic understanding for the competitive exclusion of

  1. Competition among native and invasive Impatiens species: the roles of environmental factors, population density and life stage

    PubMed Central

    Čuda, Jan; Skálová, Hana; Janovský, Zdeněk; Pyšek, Petr

    2015-01-01

    Many invasive species are considered competitively superior to native species, with the strongest competition expected in species with similar niches and/or in closely related species. However, competition outcome is strongly context-dependent as competitive strength varies along environmental gradients, and life stages, and also depends on abundances. To explore the importance of these factors, we examined competition effects in an experiment with three Impatiens species (Balsaminaceae) widespread in central Europe and sharing similar life-history characteristics and habitats: the native I. noli-tangere, and two invasive species, I. parviflora and I. glandulifera. We compared their competitive strength and reciprocal impacts under two levels of water and light availability, two overall planting densities and three competitor densities. We assessed species performance (ability to complete the life-cycle, biomass and fecundity) and temporal competition dynamics in a garden pot experiment. Environmental variables had lower explanatory power than overall planting and competitor density, which indicates the importance of competitive interactions when evaluating plant performance and potential invasion success. Despite poor and delayed germination, the invasive I. glandulifera attained dominance even at a high competitor density and was competitively superior across all treatments, exceeding the height of both congeners. Impatiens parviflora was competitively weakest, having a negligible impact on both native I. noli-tangere and invasive I. glandulifera. The intermediate competitive strength of the native I. noli-tangere probably results from its intermediate height, and good germination rate and timing. The difference in height among species increased during the experiment when I. glandulifera was involved; this species continues growing until autumn, enhancing its competitive superiority. The results provide a mechanistic understanding for the competitive exclusion of

  2. Game on: creating competitive advantages.

    PubMed

    Riskind, Patricia; Foreman, M Shane

    2004-01-01

    Whether you are opening a new imaging center or trying to keep an existing center competitive, there are 3 critical factors: customer service, marketing, and a "what's next?" attitude. Customer service: Outstanding customer service is what sticks in the minds of referring physicians and patients. Not only does providing better service differentiate you from the competition, but it also boosts employee morale and motivates people to acquire new skills. Marketing: From the front office staff to the radiologists,promoting the center should be part of every employee's job description. Simply paying lip service to the concept of marketing will not cut it. A "what's next?" attitude: Complacency is a luxury that does not exist in today's competitive health care arena. Three facilities provide examples of how these factors applied to their success.

  3. Belowground competition among invading detritivores.

    PubMed

    Chang, Chih-Han; Szlavecz, Katalin; Filley, Timothy; Buyer, Jeffrey S; Bernard, Michael J; Pitz, Scott L

    2016-01-01

    The factors regulating soil animal communities are poorly understood. Current theory favors niche complementarity and facilitation over competition as the primary forms of non-trophic interspecific interaction in soil fauna; however, competition has frequently been suggested as an important community-structuring factor in earthworms, ecosystem engineers that influence belowground processes. To date, direct evidence of competition in earthworms is lacking due to the difficulty inherent in identifying a limiting resource for saprophagous animals. In the present study, we offer the first direct evidence of interspecific competition for food in this dominant soil detritivore group by combining field observations with laboratory mesocosm experiments using 13C and 15N double-enriched leaf litter to track consumption patterns. In our experiments, the Asian invasive species Amynthas hilgendorfi was a dominant competitor for leaf litter against two European species currently invading the temperate deciduous forests in North America. This competitive advantage may account for recent invasion success of A. hilgendorfi in forests with established populations of European species, and we hypothesize that specific phenological differences play an important role in determining the outcome of the belowground competition. In contrast, Eisenoides lonnbergi, a common native species in the Eastern United States, occupied a unique trophic position with limited interactions with other species, which may contribute to its persistence in habitats dominated by invasive species. Furthermore, our results supported neither the hypothesis that facilitation occurs between species of different functional groups nor the hypothesis that species in the same group exhibit functional equivalency in C and N translocation in the soil. We propose that species identity is a more powerful approach to understand earthworm invasion and its impacts on belowground processes.

  4. Belowground competition among invading detritivores.

    PubMed

    Chang, Chih-Han; Szlavecz, Katalin; Filley, Timothy; Buyer, Jeffrey S; Bernard, Michael J; Pitz, Scott L

    2016-01-01

    The factors regulating soil animal communities are poorly understood. Current theory favors niche complementarity and facilitation over competition as the primary forms of non-trophic interspecific interaction in soil fauna; however, competition has frequently been suggested as an important community-structuring factor in earthworms, ecosystem engineers that influence belowground processes. To date, direct evidence of competition in earthworms is lacking due to the difficulty inherent in identifying a limiting resource for saprophagous animals. In the present study, we offer the first direct evidence of interspecific competition for food in this dominant soil detritivore group by combining field observations with laboratory mesocosm experiments using 13C and 15N double-enriched leaf litter to track consumption patterns. In our experiments, the Asian invasive species Amynthas hilgendorfi was a dominant competitor for leaf litter against two European species currently invading the temperate deciduous forests in North America. This competitive advantage may account for recent invasion success of A. hilgendorfi in forests with established populations of European species, and we hypothesize that specific phenological differences play an important role in determining the outcome of the belowground competition. In contrast, Eisenoides lonnbergi, a common native species in the Eastern United States, occupied a unique trophic position with limited interactions with other species, which may contribute to its persistence in habitats dominated by invasive species. Furthermore, our results supported neither the hypothesis that facilitation occurs between species of different functional groups nor the hypothesis that species in the same group exhibit functional equivalency in C and N translocation in the soil. We propose that species identity is a more powerful approach to understand earthworm invasion and its impacts on belowground processes. PMID:27008785

  5. Can NCLB Survive the Competitiveness Competition? Education Outlook. Number 2

    ERIC Educational Resources Information Center

    Hess, Frederick M.; Rotherham, Andrew J.

    2007-01-01

    Some see the George W. Bush administration's American Competitiveness Initiative (ACI) as the perfect complement to the No Child Left Behind Act's (NCLB) equity focus. The authors believe, however, that the prospects for synergy of these two agendas are not bright. In this essay, the authors discuss the history behind NCLB and the ACI, and argue…

  6. Knee pain in competitive swimming.

    PubMed

    Rodeo, S A

    1999-04-01

    The high volume of training in competitive swimming results in cumulative overload injuries. Knee pain ranks second to shoulder pain as a common complaint in competitive swimmers. Most knee pain occurs on the medial side of the knee and, most commonly, in breaststroke swimmers; however, knee pain may accompany all strokes. This article reviews the incidence of knee pain, the biomechanic and anatomic factors predisposing to injury, specific injury patterns, injury diagnosis, and the treatment and prevention of injury to the knee in swimmers. PMID:10230572

  7. 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…

  8. 23 CFR 636.404 - Can a competitive range be used to limit competition?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Can a competitive range be used to limit competition... used to limit competition? If the solicitation notifies offerors that the competitive range can be... permit an efficient competition. However, you must provide written notice to any offeror whose...

  9. 23 CFR 636.404 - Can a competitive range be used to limit competition?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Can a competitive range be used to limit competition... used to limit competition? If the solicitation notifies offerors that the competitive range can be... permit an efficient competition. However, you must provide written notice to any offeror whose...

  10. 23 CFR 636.404 - Can a competitive range be used to limit competition?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Can a competitive range be used to limit competition... used to limit competition? If the solicitation notifies offerors that the competitive range can be... permit an efficient competition. However, you must provide written notice to any offeror whose...

  11. 23 CFR 636.404 - Can a competitive range be used to limit competition?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Can a competitive range be used to limit competition... used to limit competition? If the solicitation notifies offerors that the competitive range can be... permit an efficient competition. However, you must provide written notice to any offeror whose...

  12. Competitive gut exclusion of avian pathogens by Lactobacillus acidophilus in gnotobiotic chicks.

    PubMed

    Watkins, B A; Miller, B F

    1983-09-01

    A total of 205 Grey Leghorn chicks were hatched germfree for separate trials to determine the effects of Lactobacillus acidophilus treatment on pathogenic Salmonella typhimurium and Staphlococcus aureus. Prophylactic and therapeutic treatments with L. acidophilus were administered either before or after the pathogens were introduced. Prophylactic treatments significantly reduced chick mortality (P less than .01) and shedding of the pathogens (P less than .05). The L. acidophilus prophylactic treatments were also effective qualitatively in reducing the isolation of S. typhimurium and Staph. aureus from crop contents but not, to a great extent, from cecal or rectal contents of gnotobiotic chicks at postmortem. The average surface pH values for the crop, proventriculus, duodenum, cecum, and rectum for gnotobiotic chicks were 5.43, 5.02, 6.18, 6.56, and 6.71, respectively. The L. acidophilus treatments did not significantly affect surface pH of the various segments of the intestinal tract.

  13. 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. PMID:26863856

  14. 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.

  15. Competitive exclusion of Salmonella typhimurium in broilers fed with vermicompost and complex carbohydrates.

    PubMed

    Spencer, J L; Chambers, J R; Modler, H W

    1998-01-01

    Vermicompost (VC) was produced by earthworms fed with fresh chicken faeces, and was earth-like in appearance and odour. In three experiments, VC was sprinkled on the first feed of newly-hatched broiler chicks. Treated and control groups were challenged on day 6 by the addition of seeder chicks that had been inoculated orally with Salmonella typhimurium. Chickens were killed at intervals during a 6-week period and were tested for colonization of the pathogen in the crop, caecum and internal organs. The VC-treated groups were significantly more resistant (p < 0.01) to colonization by S. typhimurium than the untreated controls. In one experiment, the VC treatment appeared to have conferred complete protection against colonization of both the crop and caecum. Colonization of the crop was increased transiently by addition to the diet of 2.5% fructooligosaccharide, xylo-oligosaccharide or transgalactosylated oligosaccharide. The influence of these carbohydrates on colonization of the caecum was variable. PMID:18484271

  16. Future survival requires competitive skills

    SciTech Connect

    Adam, P.J.

    1996-10-01

    The companies that will succeed in the global power business in 25 years will be those that best understand the productivity implications of the current power game. In the competitive free market for electricity, the inefficient will be driven out. This will include the developer that is unable to achieve higher productivity in developing and financing projects, the engineer-constructor that longs for the old risk-free, cost-plus environment and the trading company that fails to enter into new relationships with the most productive companies in the world. Also in jeopardy will be the operator who can`t reduce O and M costs and the manufacturer who is unable to control overhead or labor costs. Succeeding will be all about productivity. Free market competition drives productivity improvement. In a competitive environment, companies must operate at a more efficient level. The US learned this accidentally through the Public Utilities Regulatory Policies Act, getting us a side benefit of free market competition and lower electricity prices. In other countries the practice of socialism and its final bankruptcy forced adjustments to free market policies.

  17. Raising Economic Competitiveness with Education.

    ERIC Educational Resources Information Center

    Silberman, Harry F.

    The current school reform movement has been plagued by three false assumptions. The first of these postulates that more academic requirements will strengthen the minds of students, improve their reasoning, prepare them for a rapidly changing economy, and make the U.S. economy more competitive. Although it is true that the workers of the future…

  18. An Amusement Park Physics Competition

    ERIC Educational Resources Information Center

    Moll, Rachel F.

    2010-01-01

    Amusement park physics is a popular way to reinforce physics concepts and to motivate physics learners. This article describes a novel physics competition where students use simple tools to take amusement park ride measurements and use the data to answer challenging exam questions. Research into the impact of participating in the competition…

  19. Teaching the Values of Competition

    ERIC Educational Resources Information Center

    Buyer, Paul

    2005-01-01

    The author of this paper first learned about the values of competition as a member of the 1989 Star of Indiana Drum and Bugle Corps. Because they played more than thirty shows that summer, it was common to compete two nights in a row. He vividly remembers one such occasion. Their first show was outstanding, and they finished second. Everyone was…

  20. The components of kin competition.

    PubMed

    Van Dyken, J David

    2010-10-01

    It is well known that competition among kin alters the rate and often the direction of evolution in subdivided populations. Yet much remains unclear about the ecological and demographic causes of kin competition, or what role life cycle plays in promoting or ameliorating its effects. Using the multilevel Price equation, I derive a general equation for evolution in structured populations under an arbitrary intensity of kin competition. This equation partitions the effects of selection and demography, and recovers numerous previous models as special cases. I quantify the degree of kin competition, α, which explicitly depends on life cycle. I show how life cycle and demographic assumptions can be incorporated into kin selection models via α, revealing life cycles that are more or less permissive of altruism. As an example, I give closed-form results for Hamilton's rule in a three-stage life cycle. Although results are sensitive to life cycle in general, I identify three demographic conditions that give life cycle invariant results. Under the infinite island model, α is a function of the scale of density regulation and dispersal rate, effectively disentangling these two phenomena. Population viscosity per se does not impede kin selection.

  1. Competitive economics of nuclear power

    SciTech Connect

    Hellman, R.

    1981-03-02

    Some 12 components of a valid study of the competitive economics of a newly ordered nuclear power plant are identified and explicated. These are then used to adjust the original cost projections of four authoritative studies of nuclear and coal power economics.

  2. Competition with Charters Motivates Districts

    ERIC Educational Resources Information Center

    Holley, Marc J.; Lueken, Martin F.; Egalite, Anna J.

    2013-01-01

    Proponents of market-based education reform often argue that introducing charter schools and other school choice policies creates a competitive dynamic that will prompt low-performing districts to improve their practice. Rather than simply providing an alternative to neighborhood public schools for a handful of students, the theory says, school…

  3. Does market competition explain fairness?

    PubMed

    Descioli, Peter

    2013-02-01

    The target article by Baumard et al. uses their previous model of bargaining with outside options to explain fairness and other features of human sociality. This theory implies that fairness judgments are determined by supply and demand but humans often perceive prices (divisions of surplus) in competitive markets to be unfair.

  4. Clean Energy Business Plan Competition

    SciTech Connect

    Maxted, Sara Jane; Lojewski, Brandon; Scherson, Yaniv

    2012-01-01

    Top Students Pitch Clean Energy Business Plans The six regional finalists of the National Clean Energy Business Plan Competition pitched their business plans to a panel of judges June 13 in Washington, D.C. The expert judges announced NuMat Technologies from Northwestern University as the grand prize winner.

  5. Competitive Cooperation: The Iceberg Profile.

    ERIC Educational Resources Information Center

    Vaughan, Jerry L.

    Competitive athletes' scores on the Profile of Mood States (POMS) test create an iceberg-like pattern known as the "Iceberg Profile." Their scores for tension, depression, anger, fatigue, and confusion are low while their scores on vigor juts upward creating the "Iceberg Profile." Persons in a cooperative relationship are often competing against…

  6. Geographic Proximity and Enrollment Competition.

    ERIC Educational Resources Information Center

    Zammuto, Raymond F.

    The use of a measure of geographic proximity to help explain enrollment competition among postsecondary institutions was investigated. The measure, the number of miles between institutions, was obtained by determining the longitude and latitude coordinates for about 99% of the schools in the Higher Education General Information System universe.…

  7. Assessing the New Competitive Landscape.

    ERIC Educational Resources Information Center

    Blustain, Harvey; Goldstein, Philip; Lozier, Gregory

    1998-01-01

    Argues that complex forces (new delivery technologies, changing demographics, emergence of corporate universities, global economy) have created a new, competitive landscape for higher education that forces institutions to think methodically about how to respond. A framework for college planning, incorporating three critical components, is…

  8. A Sinking Feeling about Competition.

    ERIC Educational Resources Information Center

    Cirasuolo, Joseph J.

    2001-01-01

    A competitive school ambience will further distinguish winners from losers in an increasingly fractured and stratified society. Disadvantaged students have little chance to win the standards game. Educators should examine the gilded age's hypocrisy; what gallantry existed the night the Titanic sank applied only to first-class female passengers.…

  9. Economic Competitiveness: A Campaign Primer

    ERIC Educational Resources Information Center

    Fischer, Karin

    2008-01-01

    With the dollar's continued swoon and grim news on the job front, American economic competitiveness has become a central theme in the presidential election. Stumping in Ohio and Pennsylvania, old-line industrial states hit hard by the flight of manufacturing jobs, Democrats Hillary Rodham Clinton and Barack Obama have called for renegotiating the…

  10. Clean Energy Business Plan Competition

    ScienceCinema

    Maxted, Sara Jane; Lojewski, Brandon; Scherson, Yaniv

    2016-07-12

    Top Students Pitch Clean Energy Business Plans The six regional finalists of the National Clean Energy Business Plan Competition pitched their business plans to a panel of judges June 13 in Washington, D.C. The expert judges announced NuMat Technologies from Northwestern University as the grand prize winner.

  11. Competition in a Social Structure

    NASA Astrophysics Data System (ADS)

    Legara, Erika Fille; Longjas, Anthony; Batac, Rene

    Complex adaptive agents develop strategies in the presence of competition. In modern human societies, there is an inherent sense of locality when describing inter-agent dynamics because of its network structure. One then wonders whether the traditional advertising schemes that are globally publicized and target random individuals are as effective in attracting a larger portion of the population as those that take advantage of local neighborhoods, such as "word-of-mouth" marketing schemes. Here, we demonstrate using a differential equation model that schemes targeting local cliques within the network are more successful at gaining a larger share of the population than those that target users randomly at a global scale (e.g., television commercials, print ads, etc.). This suggests that success in the competition is dependent not only on the number of individuals in the population but also on how they are connected in the network. We further show that the model is general in nature by considering examples of competition dynamics, particularly those of business competition and language death.

  12. Disciplinary Exclusion: The Influence of School Ethos

    ERIC Educational Resources Information Center

    Hatton, Lucy Ann

    2013-01-01

    Disciplinary exclusion is a strategy used by some schools in response to challenging behaviour. While some studies have explored interventions that can be implemented to reduce the exclusion of "at risk" pupils, others have considered how the underlying school ethos influences how challenging behaviour is understood and managed. The current study…

  13. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Exclusions. 763.99 Section 763.99... Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be required to perform an inspection under § 763.85(a) in any sampling area as defined in 40 CFR 763.103...

  14. 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....

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Strategic Alternatives to Exclusion from School

    ERIC Educational Resources Information Center

    Parsons, Carl

    2009-01-01

    This original study shows that local authorities, working collaboratively with their schools and clusters, can dramatically reduce exclusions and make permanent exclusions unnecessary. And through research in three low excluding local authorities and five high excluding local authorities, it shows how this is done. The challenges and barriers are…

  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. 48 CFR 19.1504 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 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...

  3. 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...

  4. 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...

  5. 48 CFR 32.404 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Exclusions. 32.404 Section 32.404 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING Advance Payments for Non-Commercial Items 32.404 Exclusions. (a) This subpart does not apply to advance...

  6. 12 CFR 229.42 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 3 2013-01-01 2013-01-01 false Exclusions. 229.42 Section 229.42 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED) AVAILABILITY OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Collection of Checks § 229.42 Exclusions....

  7. 12 CFR 229.42 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 3 2012-01-01 2012-01-01 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....

  8. 12 CFR 229.42 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 3 2014-01-01 2014-01-01 false Exclusions. 229.42 Section 229.42 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED) AVAILABILITY OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Collection of Checks § 229.42 Exclusions....

  9. 12 CFR 229.42 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 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....

  10. Exclusion from School: The Public Cost. Revised.

    ERIC Educational Resources Information Center

    Parsons, Carl; Castle, Frances; Howlett, Keith; Worrall, John

    The true expense, in cash terms, of exclusion from school in England is investigated. Data were gathered in six English local education authorities (LEAs): two in London, two metropolitan authorities, and two country authorities. Permanent exclusion is a matter of concern to the Commission for Racial Equality because some ethnic minorities are…

  11. 7 CFR 1b.3 - Categorical exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Categorical exclusions. 1b.3 Section 1b.3 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.3 Categorical exclusions... individual or cumulative effect on the human environment and are excluded from the preparation...

  12. 7 CFR 1b.3 - Categorical exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Categorical exclusions. 1b.3 Section 1b.3 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.3 Categorical exclusions... individual or cumulative effect on the human environment and are excluded from the preparation...

  13. 33 CFR 87.3 - Exclusive use.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Exclusive use. 87.3 Section 87.3 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INLAND NAVIGATION RULES ANNEX IV: DISTRESS SIGNALS § 87.3 Exclusive use. The use or exhibition of any of the foregoing signals except for...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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.

  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. [Competitive behavior of Biomphalaria glabrata and Biomphalaria tenagophila--laboratory studies].

    PubMed

    dos Santos, M B; de Freitas, J R; Alves, E de S; Rocha, L A

    1989-10-01

    Observation about cohabitation among B. glabrata and B. tenagophila revealed a greater vulnerability of B. tenagophila population during the process of competition when its density was severely decreased in 12 trials, moderate in 2 trials. It was higher than B. glabrata in only one trial. Some snail water chemical parameters analysed such as pH, alkalinity, conductivity and oxygen dissolved, and the viability rate of batch of eggs didn't give subsidy to explain the competition mechanism. The newly-born survival, in the situation of cohabitation, was low for both species. This reveals the existence of intra and interspecific competitive interaction. The fertility rate reduction of B. tenagophila during the cohabitation was considered as a cause of its exclusion. One of the factors that seems to have influenced the fertility rate was a possible wrong crossing.

  1. Competition in the chemostat: A stochastic multi-species model and its asymptotic behavior.

    PubMed

    Xu, Chaoqun; Yuan, Sanling

    2016-10-01

    In this paper, a stochastic chemostat model in which n-species compete for a single growth-limiting substrate is considered. We first prove that the stochastic model has an unique global positive solution by using the comparison theorem for stochastic differential equations. Then we show that when the noise intensities are small, the competition outcome in the chemostat is completely determined by the species' stochastic break-even concentrations: the species with the lowest stochastic break-even concentration survives and all other species will go to extinction in the chemostat. In other words, the competitive exclusion principle holds for stochastic competition chemostat model when the noise intensities are small. Moreover, we find that noise may change the destiny of the species. Numerical simulations illustrate the obtained results. PMID:27474206

  2. Climate-driven sympatry may not lead to foraging competition between congeneric top-predators.

    PubMed

    Cimino, Megan A; Moline, Mark A; Fraser, William R; Patterson-Fraser, Donna L; Oliver, Matthew J

    2016-01-06

    Climate-driven sympatry may lead to competition for food resources between species. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. On fine scales, we tested for foraging competition between these species during the chick-rearing period by comparing their foraging behaviors with the distribution of their prey, Antarctic krill. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguins, and found that krill selected for habitats that balance the need to consume food and avoid predation. In overlapping Adélie and gentoo penguin foraging areas, four gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion of Adélie penguins by gentoo penguins. Contrary to a recent theory, which suggests that increased competition for krill is one of the major drivers of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories.

  3. Climate-driven sympatry may not lead to foraging competition between congeneric top-predators

    PubMed Central

    Cimino, Megan A.; Moline, Mark A.; Fraser, William R.; Patterson-Fraser, Donna L.; Oliver, Matthew J.

    2016-01-01

    Climate-driven sympatry may lead to competition for food resources between species. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. On fine scales, we tested for foraging competition between these species during the chick-rearing period by comparing their foraging behaviors with the distribution of their prey, Antarctic krill. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguins, and found that krill selected for habitats that balance the need to consume food and avoid predation. In overlapping Adélie and gentoo penguin foraging areas, four gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion of Adélie penguins by gentoo penguins. Contrary to a recent theory, which suggests that increased competition for krill is one of the major drivers of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories. PMID:26732496

  4. Climate-driven sympatry may not lead to foraging competition between congeneric top-predators.

    PubMed

    Cimino, Megan A; Moline, Mark A; Fraser, William R; Patterson-Fraser, Donna L; Oliver, Matthew J

    2016-01-01

    Climate-driven sympatry may lead to competition for food resources between species. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. On fine scales, we tested for foraging competition between these species during the chick-rearing period by comparing their foraging behaviors with the distribution of their prey, Antarctic krill. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguins, and found that krill selected for habitats that balance the need to consume food and avoid predation. In overlapping Adélie and gentoo penguin foraging areas, four gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion of Adélie penguins by gentoo penguins. Contrary to a recent theory, which suggests that increased competition for krill is one of the major drivers of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories. PMID:26732496

  5. Central exclusive production at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, Leszek; Guryn, Włodek; Turnau, Jacek

    2014-11-01

    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 √ {s} = 200 GeV. The preliminary spectra of two-pion mass reconstructed by STAR TPC in central region of pseudorapidity |η| < 1, are presented. Near future plans to take data with the current system at center-of-mass energy √ {s} = 200 GeV and plans to upgrade the forward proton tagging system are presented. Also a possible addition of the RPs to the sPHENIX detector is discussed.

  6. 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.

  7. 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.

  8. Central exclusive production at the Tevatron

    SciTech Connect

    Albrow, Michael G.; /Fermilab

    2008-12-01

    In CDF we have observed several exclusive processes: 2-photon {yields} e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -}, photon+pomeron {yields} J/{psi} and {psi}(2S), and pomeron+pomeron {yields} {chi}{sub c}. The cross sections agree with QED, HERA photoproduction data, and theoretical estimates of gg {yields} {chi}{sub c} with another gluon exchanged to screen the color. This observation of exclusive {chi}{sub c}, together with earlier observations of exclusive dijets and exclusive 2-photon candidates, support some theoretical predictions for p+p {yields} p+H+p at the LHC. Exclusive dileptons offer the best means of precisely calibrating forward proton spectrometers.

  9. Central Exclusive Production at the Tevatron

    SciTech Connect

    Albrow, Michael

    2009-03-23

    In CDF we have observed several exclusive processes: {gamma}{gamma}{yields}e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -}, {gamma}+IP{yields}J/{psi}, {psi}(2S) and IP+IP{yields}{chi}{sub c}. The cross sections agree with QED, HERA photoproduction data, and theoretical estimates of gg{yields}{chi}{sub c} with another gluon exchanged to screen the color. This observation of exclusive {chi}{sub c}, together with earlier observations of exclusive dijets and exclusive {gamma}{gamma} candidates, support some theoretical predictions for p+p{yields}p+SMH+p at the LHC. Exclusive dileptons offer the best means of precisely calibrating forward proton spectrometers.

  10. 42 CFR 402.308 - Waivers of exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PROVISIONS CIVIL MONEY PENALTIES, ASSESSMENTS, AND EXCLUSIONS Exclusions § 402.308 Waivers of exclusions. (a... authorization to obtain information from private health insurers, peer review organizations (including, but...

  11. Construal Level and Social Exclusion: Concrete Thinking Impedes Recovery From Social Exclusion.

    PubMed

    Pfundmair, Michaela; Lermer, Eva; Frey, Dieter; Aydin, Nilüfer

    2015-01-01

    Social exclusion is a painful experience. Recent research has shown, however, that coping with exclusion can be facilitated by favorable conditions. In the current research, we investigated whether construal level affects recovery from social exclusion. We hypothesized that an abstract vs. concrete mindset would moderate coping with exclusion. Indeed, lower compared to higher concrete thinking (Study 1) and abstract compared to concrete thinking (Study 2) bolstered the basic need of belonging when excluded. Priming of abstract thinking, moreover, increased participants' sense of belonging both in response to exclusion and inclusion relative to no priming (Study 3). Our results are the first to establish a relationship between construal level and social exclusion, thereby suggesting an alleviating "abstraction discount" effect for the consequences of social exclusion.

  12. Demolishing the Competition: The Longitudinal Link between Competitive Video Games, Competitive Gambling, and Aggression

    ERIC Educational Resources Information Center

    Adachi, Paul J. C.; Willoughby, Teena

    2013-01-01

    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…

  13. Coevolutionary patterning of teeth and taste buds

    PubMed Central

    Bloomquist, Ryan F.; Parnell, Nicholas F.; Phillips, Kristine A.; Fowler, Teresa E.; Yu, Tian Y.; Sharpe, Paul T.; Streelman, J. Todd

    2015-01-01

    Teeth and taste buds are iteratively patterned structures that line the oro-pharynx of vertebrates. Biologists do not fully understand how teeth and taste buds develop from undifferentiated epithelium or how variation in organ density is regulated. These organs are typically studied independently because of their separate anatomical location in mammals: teeth on the jaw margin and taste buds on the tongue. However, in many aquatic animals like bony fishes, teeth and taste buds are colocalized one next to the other. Using genetic mapping in cichlid fishes, we identified shared loci controlling a positive correlation between tooth and taste bud densities. Genome intervals contained candidate genes expressed in tooth and taste bud fields. sfrp5 and bmper, notable for roles in Wingless (Wnt) and bone morphogenetic protein (BMP) signaling, were differentially expressed across cichlid species with divergent tooth and taste bud density, and were expressed in the development of both organs in mice. Synexpression analysis and chemical manipulation of Wnt, BMP, and Hedgehog (Hh) pathways suggest that a common cichlid oral lamina is competent to form teeth or taste buds. Wnt signaling couples tooth and taste bud density and BMP and Hh mediate distinct organ identity. Synthesizing data from fish and mouse, we suggest that the Wnt-BMP-Hh regulatory hierarchy that configures teeth and taste buds on mammalian jaws and tongues may be an evolutionary remnant inherited from ancestors wherein these organs were copatterned from common epithelium. PMID:26483492

  14. Coevolutionary patterning of teeth and taste buds.

    PubMed

    Bloomquist, Ryan F; Parnell, Nicholas F; Phillips, Kristine A; Fowler, Teresa E; Yu, Tian Y; Sharpe, Paul T; Streelman, J Todd

    2015-11-01

    Teeth and taste buds are iteratively patterned structures that line the oro-pharynx of vertebrates. Biologists do not fully understand how teeth and taste buds develop from undifferentiated epithelium or how variation in organ density is regulated. These organs are typically studied independently because of their separate anatomical location in mammals: teeth on the jaw margin and taste buds on the tongue. However, in many aquatic animals like bony fishes, teeth and taste buds are colocalized one next to the other. Using genetic mapping in cichlid fishes, we identified shared loci controlling a positive correlation between tooth and taste bud densities. Genome intervals contained candidate genes expressed in tooth and taste bud fields. sfrp5 and bmper, notable for roles in Wingless (Wnt) and bone morphogenetic protein (BMP) signaling, were differentially expressed across cichlid species with divergent tooth and taste bud density, and were expressed in the development of both organs in mice. Synexpression analysis and chemical manipulation of Wnt, BMP, and Hedgehog (Hh) pathways suggest that a common cichlid oral lamina is competent to form teeth or taste buds. Wnt signaling couples tooth and taste bud density and BMP and Hh mediate distinct organ identity. Synthesizing data from fish and mouse, we suggest that the Wnt-BMP-Hh regulatory hierarchy that configures teeth and taste buds on mammalian jaws and tongues may be an evolutionary remnant inherited from ancestors wherein these organs were copatterned from common epithelium.

  15. Characterization of an antibiotic resistant clostridium hathewayi strain from a continuous flow exclusion chemostat culture derived from the cecal contents of a feral pig

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemostat model has been an important tool in studying intestinal microflora. To date, several competitive exclusion products have been developed from such studies as prophylactic treatment against pathogenic bacteria. A continuous flow chemostat model of a feral pig was developed using inocul...

  16. Modeling competition between yeast strains

    NASA Astrophysics Data System (ADS)

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap

    2016-04-01

    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  17. Arizona network improves providers' competitiveness.

    PubMed

    Lipson, E H; McHaney, J E

    1987-01-01

    In the September/October issue of Physician Executive, the Remote Practice Network (RPN) health care delivery system concept was introduced and explained. In this article, the concept is illustrated by a description of Arizona HealthSource (AHS), an RPN developed in Phoenix, Arizona. AHS's design, evolution, and operation demonstrate both the competitive pressures that force hospitals into taking new initiatives and the exciting alternative offered by an RPN. Arizona HealthSource serves the Phoenix, Ariz., region, a highly competitive health care marketplace. The organization was started by St. Joseph's Hospital and Medical Center in cooperation with Magliaro & McHaney, a consulting firm with offices in Atlanta, Ga., and La Jolla, Calif. AHS is currently managed under contract by Magliaro & McHaney, which develop the RPN concept and which designs, implements, markets, and manages health care delivery system. PMID:10312349

  18. BDS thin film damage competition

    SciTech Connect

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  19. FIRST teams watch the competition

    NASA Technical Reports Server (NTRS)

    2000-01-01

    FIRST teams watch robots in action during the FIRST competition. Students from all over the country are at the KSC Visitor Complex for the FIRST (For Inspiration and Recognition of Science and Technology) Southeast Regional competition March 9-11 in the Rocket Garden. Teams of high school students are testing the limits of their imagination using robots they have designed, with the support of business and engineering professionals and corporate sponsors, to compete in a technological battle against other schools' robots. Of the 30 high school teams competing, 16 are Florida teams co-sponsored by NASA and KSC contractors. Local high schools participating are Astronaut, Bayside, Cocoa Beach, Eau Gallie, Melbourne, Melbourne Central Catholic, Palm Bay, Rockledge, Satellite, and Titusville.

  20. Plan competitions reveal entrepreneurial talent

    SciTech Connect

    Madison, Alison L.

    2011-05-15

    Monthly economic diversity column for Tri-City Herald business section. Excerpt below: There’s something to be said for gaining valuable real-world experience in a structured, nurturing environment. Take for instance learning to scuba dive in the comfort of my resort pool rather than immediately hanging out with sharks while I figure out little things like oxygen tanks and avoiding underwater panic attacks. Likewise, graduate students are getting some excellent, supportive real-world training through university business plan competitions. These competitions are places where smart minds, new technologies, months of preparation and coaching, and some healthy pre-presentation jitters collide to reveal not only solid new business ideas, but also some promising entrepreneurial talent. In fact, professionals from around our region descend upon college campuses every spring to judge these events, which help to bridge the gap between academics and the real technology and business-driven economy.

  1. Microscale Titration in Schools Titration Competition.

    ERIC Educational Resources Information Center

    Clark, Michael J.

    1998-01-01

    Reviews the requirements of the National Titration Competition and describes how a team in a local competition used the technique. Compares microscale titration to conventional titration. Outlines the benefits of employing microscale techniques. (DDR)

  2. 77 FR 2676 - Competitive Postal Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-19

    ... Postal Service an artificial competitive advantage. The Commission gave considerable weight to the... 39 CFR Part 3015 Competitive Postal Products AGENCY: Postal Regulatory Commission. ACTION: Notice of proposed rulemaking. SUMMARY: The Commission is initiating a review to determine whether...

  3. Competitive Intelligence and the Information Center.

    ERIC Educational Resources Information Center

    Greene, H. Frances

    1988-01-01

    Examines the competitive intelligence approach to corporate information gathering, and discusses how it differs from the traditional library information center approach. Steps for developing a competitive intelligence system in the library information center are suggested. (33 references) (MES)

  4. Developing Information Systems for Competitive Intelligence Support.

    ERIC Educational Resources Information Center

    Hohhof, Bonnie

    1994-01-01

    Discusses issues connected with developing information systems for competitive intelligence support; defines the elements of an effective competitive information system; and summarizes issues affecting system design and implementation. Highlights include intelligence information; information needs; information sources; decision making; and…

  5. 48 CFR 245.7302 - Competitive sales.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Competitive sales. 245..., DEPARTMENT OF DEFENSE CONTRACT MANAGEMENT GOVERNMENT PROPERTY Sale of Surplus Contractor Inventory 245.7302 Competitive sales....

  6. 43 CFR 3120.5 - Competitive sale.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Competitive sale. 3120.5 Section 3120.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT... Competitive sale....

  7. 43 CFR 3120.5 - Competitive sale.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Competitive sale. 3120.5 Section 3120.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT... Competitive sale....

  8. 43 CFR 3120.5 - Competitive sale.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Competitive sale. 3120.5 Section 3120.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT... Competitive sale....

  9. 43 CFR 3120.5 - Competitive sale.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Competitive sale. 3120.5 Section 3120.5 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT... Competitive sale....

  10. Managed competition: the policy context.

    PubMed

    Scotton, R

    1999-01-01

    In order to maintain universal access to medically effective care for all, costs must be contained at both the system-wide and micro levels. The managed competition model offers a framework within which increased efficiency could be pursued without sacrificing the goal of universal access and without impairing health outcomes and social cohesion. It would do this by removing structural impediments to rational decision-making and allocating to markets and governments the functions they perform best. PMID:10558292

  11. Physiological demands of competitive surfing.

    PubMed

    Farley, Oliver R L; Harris, Nigel K; Kilding, Andrew E

    2012-07-01

    This study was a performance analysis of surfing athletes during competitive surfing events in an attempt to inform the development of surfing-specific conditioning. Twelve nationally ranked surfers were fitted with heart rate (HR) monitors and global positioning system (GPS) units and videoed during the heats of 2 sanctioned competitions. Means and SDs represented the centrality and spread of analyzed data. From the 32 videos analyzed, the greatest amount of time spent during surfing was paddling (54 ± 6.3% of the total time) (% TT). The remaining stationary represented 28 ± 6.9% TT, wave riding, and paddling for a wave represented only 8 ± 2% TT and 4 ± 1.5% TT, respectively. Surfers spent 61 ± 7% of the total paddling bouts and 64 ± 6.8% of total stationary bouts between 1 and 10 seconds. The average speed recorded via the GPS for all the subjects was 3.7 ± 0.6 km·h(-1), with an average maximum speed of 33.4 ± 6.5 km·h(-1) (45 km·h(-1) was the highest speed recorded). The average distance covered was 1,605 ± 313 m. The mean HR during the surf competitions was 139 ± 11 b·min(-1) (64% HRmax), with a (mean) peak of 190 ± 12 b·min(-1) (87% HRmax). Sixty percent TT was spent between 56 and 74% of the age-predicted HR maximum (HRmax), 19% TT >46% HRmax, and approximately 3% TT >83% HRmax. Competitive surfing therefore involves intermittent high-intensity bouts of all out paddling intercalated with relatively short recovery periods and repeated bouts of low-intensity paddling, incorporating intermittent breath holding. Surfing-specific conditioning sessions should attempt to replicate such a profile. PMID:21986691

  12. 7 CFR 1738.210 - Competitive analysis.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 11 2013-01-01 2013-01-01 false Competitive analysis. 1738.210 Section 1738.210... Competitive analysis. The applicant must submit a competitive market analysis for each service area regardless of projected penetration rates. Each analysis must identify all existing service providers and...

  13. 7 CFR 1738.210 - Competitive analysis.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 11 2012-01-01 2012-01-01 false Competitive analysis. 1738.210 Section 1738.210... Competitive analysis. The applicant must submit a competitive market analysis for each service area regardless of projected penetration rates. Each analysis must identify all existing service providers and...

  14. 7 CFR 1738.210 - Competitive analysis.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 11 2014-01-01 2014-01-01 false Competitive analysis. 1738.210 Section 1738.210... Competitive analysis. The applicant must submit a competitive market analysis for each service area regardless of projected penetration rates. Each analysis must identify all existing service providers and...

  15. 7 CFR 550.46 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 6 2011-01-01 2011-01-01 false Competition. 550.46 Section 550.46 Agriculture... Procurement Standards § 550.46 Competition. (a) All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The Cooperator shall be alert...

  16. 14 CFR 1274.504 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Competition. 1274.504 Section 1274.504... FIRMS Procurement Standards § 1274.504 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall...

  17. 7 CFR 3019.43 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Competition. 3019.43 Section 3019.43 Agriculture... § 3019.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  18. 22 CFR 518.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 2 2012-04-01 2009-04-01 true Competition. 518.43 Section 518.43 Foreign... Procurement Standards § 518.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert...

  19. 14 CFR 1274.504 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Competition. 1274.504 Section 1274.504... FIRMS Procurement Standards § 1274.504 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall...

  20. 28 CFR 70.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Competition. 70.43 Section 70.43 Judicial... Post-Award Requirements Procurement Standards § 70.43 Competition. All procurement transactions must be conducted in a manner to provide, to the maximum extent practical, open and free competition. The...

  1. 20 CFR 435.43 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Competition. 435.43 Section 435.43 Employees...-Award Requirements Procurement Standards § 435.43 Competition. All procurement transactions must be conducted in a manner to provide, to the maximum extent practical, open and free competition. The...

  2. 7 CFR 3019.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Competition. 3019.43 Section 3019.43 Agriculture... § 3019.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  3. 36 CFR 1210.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Competition. 1210.43 Section... Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to organizational conflicts of...

  4. 2 CFR 215.43 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2 Grants and Agreements 1 2011-01-01 2011-01-01 false Competition. 215.43 Section 215.43 Grants... A-110) Post Award Requirements Procurement Standards § 215.43 Competition. All procurement... competition. The recipient shall be alert to organizational conflicts of interest as well as...

  5. 48 CFR 13.104 - Promoting competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Promoting competition. 13... METHODS AND CONTRACT TYPES SIMPLIFIED ACQUISITION PROCEDURES Procedures 13.104 Promoting competition. The contracting officer must promote competition to the maximum extent practicable to obtain supplies and...

  6. 7 CFR 550.5 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 6 2011-01-01 2011-01-01 false Competition. 550.5 Section 550.5 Agriculture... Competition. REE agencies may enter into non-assistance cooperative agreements, as authorized by this part, without regard to any requirements for competition. (7 U.S.C. 3318(e))....

  7. 22 CFR 145.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Competition. 145.43 Section 145.43 Foreign... Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to organizational conflicts of...

  8. 7 CFR 3019.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Competition. 3019.43 Section 3019.43 Agriculture... § 3019.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  9. 49 CFR 19.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Competition. 19.43 Section 19.43 Transportation... Requirements Procurement Standards § 19.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall...

  10. 38 CFR 49.43 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2014-07-01 2014-07-01 false Competition. 49.43... NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 49.43 Competition. All... free competition. The recipient shall be alert to organizational conflicts of interest as well...

  11. 43 CFR 12.943 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Competition. 12.943 Section 12.943 Public....943 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  12. 28 CFR 70.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Competition. 70.43 Section 70.43 Judicial... Post-Award Requirements Procurement Standards § 70.43 Competition. All procurement transactions must be conducted in a manner to provide, to the maximum extent practical, open and free competition. The...

  13. 48 CFR 570.104 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Competition. 570.104... PROGRAMS ACQUIRING LEASEHOLD INTERESTS IN REAL PROPERTY General 570.104 Competition. Unless the contracting officer uses the simplified procedures in subpart 570.2, the competition requirements of FAR part 6...

  14. 48 CFR 570.104 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Competition. 570.104... PROGRAMS ACQUIRING LEASEHOLD INTERESTS IN REAL PROPERTY General 570.104 Competition. Unless the contracting officer uses the simplified procedures in subpart 570.2, the competition requirements of FAR part 6...

  15. 7 CFR 550.5 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 6 2012-01-01 2012-01-01 false Competition. 550.5 Section 550.5 Agriculture... Competition. REE agencies may enter into non-assistance cooperative agreements, as authorized by this part, without regard to any requirements for competition. (7 U.S.C. 3318(e))....

  16. 43 CFR 12.943 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Competition. 12.943 Section 12.943 Public....943 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  17. 48 CFR 1353.206 - Competition requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... FORMS FORMS Prescription of Forms 1353.206 Competition requirements. As prescribed in 48 CFR 1306.303-70, use Form CD-492, Justification for Other Than Full and Open Competition, to support the requirements... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Competition...

  18. 48 CFR 1353.206 - Competition requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... FORMS FORMS Prescription of Forms 1353.206 Competition requirements. As prescribed in 48 CFR 1306.303-70, use Form CD-492, Justification for Other Than Full and Open Competition, to support the requirements... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Competition...

  19. 45 CFR 74.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Competition. 74.43 Section 74.43 Public Welfare... COMMERCIAL ORGANIZATIONS Post-Award Requirements Procurement Standards § 74.43 Competition. All procurement... competition. The recipient shall be alert to organizational conflicts of interest as well as...

  20. 49 CFR 19.43 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Competition. 19.43 Section 19.43 Transportation... Requirements Procurement Standards § 19.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall...

  1. 48 CFR 570.203-2 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Competition. 570.203-2... 570.203-2 Competition. (a) To the maximum extent practicable, the contracting officer must solicit at least three sources to promote competition. If there are repeated requirements for space in the...

  2. 36 CFR 1210.43 - Competition.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Competition. 1210.43 Section... Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to organizational conflicts of...

  3. 40 CFR 30.43 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Competition. 30.43 Section 30.43... NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 30.43 Competition. All... free competition. The recipient shall be alert to organizational conflicts of interest as well...

  4. 48 CFR 9.206-3 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Competition. 9.206-3... CONTRACTOR QUALIFICATIONS Qualifications Requirements 9.206-3 Competition. (a) Presolicitation. If a... solicitation to ascertain whether the number of sources is adequate for competition. (See 9.204(a) for...

  5. 29 CFR 95.43 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 1 2011-07-01 2011-07-01 false Competition. 95.43 Section 95.43 Labor Office of the... Standards § 95.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert...

  6. 29 CFR 95.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 1 2013-07-01 2013-07-01 false Competition. 95.43 Section 95.43 Labor Office of the... Standards § 95.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert...

  7. 48 CFR 570.104 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Competition. 570.104... PROGRAMS ACQUIRING LEASEHOLD INTERESTS IN REAL PROPERTY General 570.104 Competition. Unless the contracting officer uses the simplified procedures in subpart 570.2, the competition requirements of FAR part 6...

  8. 43 CFR 12.943 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Competition. 12.943 Section 12.943 Public....943 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to...

  9. 20 CFR 435.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Competition. 435.43 Section 435.43 Employees...-Award Requirements Procurement Standards § 435.43 Competition. All procurement transactions must be conducted in a manner to provide, to the maximum extent practical, open and free competition. The...

  10. 45 CFR 2400.2 - Annual competition.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Annual competition. 2400.2 Section 2400.2 Public... FELLOWSHIP PROGRAM REQUIREMENTS General § 2400.2 Annual competition. To achieve its principal purposes, the Foundation holds an annual national competition to select teachers in grades 7-12, college seniors,...

  11. 48 CFR 873.104 - Competition requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Competition requirements... Competition requirements. (a) Without regard to FAR part 6, if the health-care resource required is a... officers must seek competition to the maximum extent practicable and must permit all responsible...

  12. 40 CFR 35.936-3 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Competition. 35.936-3 Section 35.936-3... ASSISTANCE Grants for Construction of Treatment Works-Clean Water Act § 35.936-3 Competition. EPA's policy is to encourage free and open competition appropriate to the type of project work to be performed....

  13. 45 CFR 2400.2 - Annual competition.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Annual competition. 2400.2 Section 2400.2 Public... FELLOWSHIP PROGRAM REQUIREMENTS General § 2400.2 Annual competition. To achieve its principal purposes, the Foundation holds an annual national competition to select teachers in grades 7-12, college seniors,...

  14. 48 CFR 1353.206 - Competition requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... FORMS FORMS Prescription of Forms 1353.206 Competition requirements. As prescribed in 48 CFR 1306.303-70, use Form CD-492, Justification for Other Than Full and Open Competition, to support the requirements... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Competition...

  15. 22 CFR 145.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Competition. 145.43 Section 145.43 Foreign... Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert to organizational conflicts of...

  16. 22 CFR 518.43 - Competition.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Competition. 518.43 Section 518.43 Foreign... Procurement Standards § 518.43 Competition. All procurement transactions shall be conducted in a manner to provide, to the maximum extent practical, open and free competition. The recipient shall be alert...

  17. 48 CFR 34.005-1 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Competition. 34.005-1... OF CONTRACTING MAJOR SYSTEM ACQUISITION General 34.005-1 Competition. (a) The program manager shall, throughout the acquisition process, promote full and open competition and sustain effective...

  18. 40 CFR 35.936-3 - Competition.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Competition. 35.936-3 Section 35.936-3... ASSISTANCE Grants for Construction of Treatment Works-Clean Water Act § 35.936-3 Competition. EPA's policy is to encourage free and open competition appropriate to the type of project work to be performed....

  19. 48 CFR 873.104 - Competition requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Competition requirements... Competition requirements. (a) Without regard to FAR part 6, if the health-care resource required is a... officers must seek competition to the maximum extent practicable and must permit all responsible...

  20. 38 CFR 49.43 - Competition.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Competition. 49.43... NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 49.43 Competition. All... free competition. The recipient shall be alert to organizational conflicts of interest as well...