WorldWideScience

Sample records for belowground competition effects

  1. Earthworm and belowground competition effects on plant productivity in a plant diversity gradient.

    Science.gov (United States)

    Eisenhauer, Nico; Milcu, Alexandru; Nitschke, Norma; Sabais, Alexander C W; Scherber, Christoph; Scheu, Stefan

    2009-08-01

    Diversity is one major factor driving plant productivity in temperate grasslands. Although decomposers like earthworms are known to affect plant productivity, interacting effects of plant diversity and earthworms on plant productivity have been neglected in field studies. We investigated in the field the effects of earthworms on plant productivity, their interaction with plant species and functional group richness, and their effects on belowground plant competition. In the framework of the Jena Experiment we determined plant community productivity (in 2004 and 2007) and performance of two phytometer plant species [Centaurea jacea (herb) and Lolium perenne (grass); in 2007 and 2008] in a plant species (from one to 16) and functional group richness gradient (from one to four). We sampled earthworm subplots and subplots with decreased earthworm density and reduced aboveground competition of phytometer plants by removing the shoot biomass of the resident plant community. Earthworms increased total plant community productivity (+11%), legume shoot biomass (+35%) and shoot biomass of the phytometer C. jacea (+21%). Further, phytometer performance decreased, i.e. belowground competition increased, with increasing plant species and functional group richness. Although single plant functional groups benefited from higher earthworm numbers, the effects did not vary with plant species and functional group richness. The present study indicates that earthworms indeed affect the productivity of semi-natural grasslands irrespective of the diversity of the plant community. Belowground competition increased with increasing plant species diversity. However, belowground competition was modified by earthworms as reflected by increased productivity of the phytometer C. jacea. Moreover, particularly legumes benefited from earthworm presence. Considering also previous studies, we suggest that earthworms and legumes form a loose mutualistic relationship affecting essential ecosystem

  2. Effects of above- and below-ground competition from shrubs on photosynthesis, transpiration and growth in Quercus robur L

    Science.gov (United States)

    Anna M. Jensen; Magnus Lof; Emile S. Gardiner

    2011-01-01

    For a tree seedling to successfully establish in dense shrubbery, it must maintain function under heterogeneous resource availability. We evaluated leaf-level acclimation in photosynthetic capacity, seedling-level transpiration, and seedling morphology and growth to gain an understanding of the effects of above- and below-ground competition on Quercus robur seedlings....

  3. Belowground competition from overstory trees influences Douglas-fir sapling morphology in thinned stands

    Science.gov (United States)

    Warren D. Devine; Timothy B. Harrington

    2009-01-01

    We evaluated effects of belowground competition on morphology of naturally established coast Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) saplings in 60- to 80-year-old thinned Douglas-fir stands in southwestern Washington. We separately quantified belowground competition from overstory and understory sources...

  4. Belowground Competition Directs Spatial Patterns of Seedling Growth in Boreal Pine Forests in Fennoscandia

    Directory of Open Access Journals (Sweden)

    E. Petter Axelsson

    2014-09-01

    Full Text Available Aboveground competition is often argued to be the main process determining patterns of natural forest regeneration. However, the theory of multiple resource limitation suggests that seedling performance also depends on belowground competition and, thus, that their relative influence is of fundamental importance. Two approaches were used to address the relative importance of above- and below-ground competition on regeneration in a nutrient-poor pine (Pinus sylvestris boreal forest. Firstly, seedling establishment beneath trees stem-girdled 12 years ago show that a substantial proportion of the seedlings were established within two years after girdling, which corresponds to a time when nutrient uptake by tree roots was severely reduced without disrupting water transport to the tree canopy, which consequently was maintained. The establishment during these two years also corresponds to abundances high enough for normal stand replacement. Secondly, surveys of regeneration within forest gaps showed that surrounding forests depressed seedlings, so that satisfactory growth occurred only more than 5 m from forest edges and that higher solar radiation in south facing edges was not enough to mediate these effects. We conclude that disruption of belowground competitive interactions mediates regeneration and, thus, that belowground competition has a strong limiting influence on seedling establishment in these forests.

  5. Above- and belowground competition from longleaf pine plantations limits performance of reintroduced herbaceous species.

    Energy Technology Data Exchange (ETDEWEB)

    T.B. Harrington; C.M. Dagley; M.B. Edwards.

    2003-10-01

    Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14 perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and below-ground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1-0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.

  6. Early root overproduction not triggered by nutrients decisive for competitive success belowground

    NARCIS (Netherlands)

    Padilla, F.M.; Mommer, L.; Caluwe, de H.; Smit-Tiekstra, A.E.; Wagemaker, C.A.M.; Ouborg, N.J.; Kroon, de H.

    2013-01-01

    Background - Theory predicts that plant species win competition for a shared resource by more quickly preempting the resource in hotspots and by depleting resource levels to lower concentrations than its competitors. Competition in natural grasslands largely occurs belowground, but information

  7. Assessment of Above- and Below-ground Competition between Sesame (Sesamume indicum L. and Pigweed (Amaranthus retroflexus and Its Effects on Sesame Yield and Yield Components

    Directory of Open Access Journals (Sweden)

    A.J Yanegh

    2013-08-01

    Full Text Available This study carried out in a factorial layout on completely randomaized block design with three replications, to evaluate the above- and below- ground competition between sesame (Sesamum indicum and pigweed (Amaranthus retroflexus, and their impacts on sesame yield and yield component. The experimental treatments were all combination of crop-weed competition (shoot competition, root competition and root-shoot competition and sesame plant densitys (1, 2 and 4 plant per pot. Plants were sown in plastic pots (24 cm diameter and 28 cm height in year 2010, at feild of Ferdowsi University of Mashhad. For study the shoot competition of sesame-pigweed, the roots were separated by plastic when the pots were filled with soil before sowing the seeds. Three weeks after emerging, shoots of plants were separated vertical barrier (30 x 70 cm for studing root competition. Results showed that competition treatments had a significant effect on seed weight per plant and yield components except 1000 seed weight. Among competition produced higher yield and yield components compared to othere treatments. However, sesame and pigweed biological weight in root-shoot competition was 2.6 and 13.7 respectively, that was higher than other competition treatments and was significant. Capsule number in main and sub branches, capsule number in plant, seed number in capsule and seed number in plant in complete competition treatment was 15, 2.58, 17.5, 43.7 and 693.89 respectively, that was higher than other treatments and differences among them was significant. Sesame density also had a significant effect on seed weight per plant and yield components. When low density were used (one plant, yield and yield components was more, therefore in one plant per pot density biological weight of sesame was 3.82 gr, and in higher densities the mentioned traits decreased significantly.

  8. Early root overproduction not triggered by nutrients decisive for competitive success belowground.

    Science.gov (United States)

    Padilla, Francisco M; Mommer, Liesje; de Caluwe, Hannie; Smit-Tiekstra, Annemiek E; Wagemaker, Cornelis A M; Ouborg, N Joop; de Kroon, Hans

    2013-01-01

    Theory predicts that plant species win competition for a shared resource by more quickly preempting the resource in hotspots and by depleting resource levels to lower concentrations than its competitors. Competition in natural grasslands largely occurs belowground, but information regarding root interactions is limited, as molecular methods quantifying species abundance belowground have only recently become available. In monoculture, the grass Festuca rubra had higher root densities and a faster rate of soil nitrate depletion than Plantago lanceolata, projecting the first as a better competitor for nutrients. However, Festuca lost in competition with Plantago. Plantago not only replaced the lower root mass of its competitor, but strongly overproduced roots: with only half of the plants in mixture than in monoculture, Plantago root densities in mixture were similar or higher than those in its monocultures. These responses occurred equally in a nutrient-rich and nutrient-poor soil layer, and commenced immediately at the start of the experiment when root densities were still low and soil nutrient concentrations high. Our results suggest that species may achieve competitive superiority for nutrients by root growth stimulation prior to nutrient depletion, induced by the presence of a competitor species, rather than by a better ability to compete for nutrients per se. The root overproduction by which interspecific neighbors are suppressed independent of nutrient acquisition is consistent with predictions from game theory. Our results emphasize that root competition may be driven by other mechanisms than is currently assumed. The long-term consequences of these mechanisms for community dynamics are discussed.

  9. Legacy effects of aboveground–belowground interactions

    NARCIS (Netherlands)

    Kostenko, O.; Van de Voorde, T.F.J.; Mulder, P.P.J.; Van der Putten, W.H.; Bezemer, T.M.

    2012-01-01

    Root herbivory can greatly affect the performance of aboveground insects via changes in plant chemistry. These interactions have been studied extensively in experiments where aboveground and belowground insects were feeding on the same plant. However, little is known about how aboveground and

  10. Legacy effects of aboveground-belowground interactions

    NARCIS (Netherlands)

    Kostenko, O.; Voorde, van de T.F.J.; Mulder, P.P.J.; Putten, van der W.H.; Bezemer, T.M.

    2012-01-01

    Root herbivory can greatly affect the performance of aboveground insects via changes in plant chemistry. These interactions have been studied extensively in experiments where aboveground and belowground insects were feeding on the same plant. However, little is known about how aboveground and

  11. Effects of an Ecosystem Engineer on Belowground Movement of Microarthropods

    Science.gov (United States)

    Cameron, Erin K.; Proctor, Heather C.; Bayne, Erin M.

    2013-01-01

    Ecosystem engineers affect other species by changing physical environments. Such changes may influence movement of organisms, particularly belowground where soil permeability can restrict dispersal. We investigated whether earthworms, iconic ecosystem engineers, influence microarthropod movement. Our experiment tested whether movement is affected by tunnels (i.e., burrows), earthworm excreta (mucus, castings), or earthworms themselves. Earthworm burrows form tunnel networks that may facilitate movement. This effect may be enhanced by excreta, which could provide resources for microarthropods moving along the network. Earthworms may also promote movement via phoresy. Conversely, negative effects could occur if earthworms alter predator-prey relationships or change competitive interactions between microarthropods. We used microcosms consisting of a box connecting a “source” container in which microarthropods were present and a “destination” container filled with autoclaved soil. Treatments were set up within the boxes, which also contained autoclaved soil, as follows: 1) control with no burrows; 2) artificial burrows with no excreta; 3) abandoned burrows with excreta but no earthworms; and 4) earthworms (Lumbricus rubellus) present in burrows. Half of the replicates were sampled once after eight days, while the other half were sampled repeatedly to examine movement over time. Rather than performing classical pairwise comparisons to test our hypotheses, we used AICc to assess support for three competing models (presence of tunnels, excreta, and earthworms). More individuals of Collembola, Mesostigmata, and all microarthropods together dispersed when tunnels were present. Models that included excreta and earthworms were less well supported. Total numbers of dispersing Oribatida and Prostigmata+Astigmata were not well explained by any models tested. Further research is needed to examine the impact of soil structure and ecosystem engineering on movement

  12. Effects of an ecosystem engineer on belowground movement of microarthropods.

    Directory of Open Access Journals (Sweden)

    Erin K Cameron

    Full Text Available Ecosystem engineers affect other species by changing physical environments. Such changes may influence movement of organisms, particularly belowground where soil permeability can restrict dispersal. We investigated whether earthworms, iconic ecosystem engineers, influence microarthropod movement. Our experiment tested whether movement is affected by tunnels (i.e., burrows, earthworm excreta (mucus, castings, or earthworms themselves. Earthworm burrows form tunnel networks that may facilitate movement. This effect may be enhanced by excreta, which could provide resources for microarthropods moving along the network. Earthworms may also promote movement via phoresy. Conversely, negative effects could occur if earthworms alter predator-prey relationships or change competitive interactions between microarthropods. We used microcosms consisting of a box connecting a "source" container in which microarthropods were present and a "destination" container filled with autoclaved soil. Treatments were set up within the boxes, which also contained autoclaved soil, as follows: 1 control with no burrows; 2 artificial burrows with no excreta; 3 abandoned burrows with excreta but no earthworms; and 4 earthworms (Lumbricus rubellus present in burrows. Half of the replicates were sampled once after eight days, while the other half were sampled repeatedly to examine movement over time. Rather than performing classical pairwise comparisons to test our hypotheses, we used AIC(c to assess support for three competing models (presence of tunnels, excreta, and earthworms. More individuals of Collembola, Mesostigmata, and all microarthropods together dispersed when tunnels were present. Models that included excreta and earthworms were less well supported. Total numbers of dispersing Oribatida and Prostigmata+Astigmata were not well explained by any models tested. Further research is needed to examine the impact of soil structure and ecosystem engineering on movement

  13. Early root overproduction not triggered by nutrients decisive for competitive success belowground.

    Directory of Open Access Journals (Sweden)

    Francisco M Padilla

    Full Text Available Theory predicts that plant species win competition for a shared resource by more quickly preempting the resource in hotspots and by depleting resource levels to lower concentrations than its competitors. Competition in natural grasslands largely occurs belowground, but information regarding root interactions is limited, as molecular methods quantifying species abundance belowground have only recently become available.In monoculture, the grass Festuca rubra had higher root densities and a faster rate of soil nitrate depletion than Plantago lanceolata, projecting the first as a better competitor for nutrients. However, Festuca lost in competition with Plantago. Plantago not only replaced the lower root mass of its competitor, but strongly overproduced roots: with only half of the plants in mixture than in monoculture, Plantago root densities in mixture were similar or higher than those in its monocultures. These responses occurred equally in a nutrient-rich and nutrient-poor soil layer, and commenced immediately at the start of the experiment when root densities were still low and soil nutrient concentrations high.Our results suggest that species may achieve competitive superiority for nutrients by root growth stimulation prior to nutrient depletion, induced by the presence of a competitor species, rather than by a better ability to compete for nutrients per se. The root overproduction by which interspecific neighbors are suppressed independent of nutrient acquisition is consistent with predictions from game theory. Our results emphasize that root competition may be driven by other mechanisms than is currently assumed. The long-term consequences of these mechanisms for community dynamics are discussed.

  14. Plant genetic variation mediates an indirect ecological effect between belowground earthworms and aboveground aphids.

    Science.gov (United States)

    Singh, Akanksha; Braun, Julia; Decker, Emilia; Hans, Sarah; Wagner, Agnes; Weisser, Wolfgang W; Zytynska, Sharon E

    2014-10-21

    Interactions between aboveground and belowground terrestrial communities are often mediated by plants, with soil organisms interacting via the roots and aboveground organisms via the shoots and leaves. Many studies now show that plant genetics can drive changes in the structure of both above and belowground communities; however, the role of plant genetic variation in mediating aboveground-belowground interactions is still unclear. We used an earthworm-plant-aphid model system with two aphid species (Aphis fabae and Acyrthosiphon pisum) to test the effect of host-plant (Vicia faba) genetic variation on the indirect interaction between the belowground earthworms (Eisenia veneta) on the aboveground aphid populations. Our data shows that host-plant variety mediated an indirect ecological effect of earthworms on generalist black bean aphids (A. fabae), with earthworms increasing aphid growth rate in three plant varieties but decreasing it in another variety. We found no effect of earthworms on the second aphid species, the pea aphid (A. pisum), and no effect of competition between the aphid species. Plant biomass was increased when earthworms were present, and decreased when A. pisum was feeding on the plant (mediated by plant variety). Although A. fabae aphids were influenced by the plants and worms, they did not, in turn, alter plant biomass. Previous work has shown inconsistent effects of earthworms on aphids, but we suggest these differences could be explained by plant genetic variation and variation among aphid species. This study demonstrates that the outcome of belowground-aboveground interactions can be mediated by genetic variation in the host-plant, but depends on the identity of the species involved.

  15. Above- and below-ground competition in high and low irradiance: tree seedling responses to a competing liana Byttneria grandifolia

    NARCIS (Netherlands)

    Chen, J.Y.; Bongers, F.; Cao, K.F.; Cai, Z.Q.

    2008-01-01

    Abstract: In tropical forests, trees compete not only with other trees, but also with lianas, which may limit tree growth and regeneration. Liana effects may depend on the availability of above- and below-ground resources and differ between tree species. We conducted a shade house experiment to test

  16. The relative importance of above- versus belowground competition for tree growth and survival during early succession of a tropical moist forest

    NARCIS (Netherlands)

    Breugel, van M.; Breugel, van P.; Jansen, P.A.; Martinez-Ramos, M.; Bongers, F.

    2012-01-01

    Competition between neighboring plants plays a major role in the population dynamics of tree species in the early phases of humid tropical forest succession. We evaluated the relative importance of above- versus below-ground competition during the first years of old-field succession on soil with low

  17. Use of innovative groundcovers in Mediterranean afforestations: aerial and belowground effects in hybrid walnut.

    Directory of Open Access Journals (Sweden)

    Angelo Vitone

    2016-11-01

    Full Text Available Forest restoration in the Mediterranean area is particularly limited by water scarcity in summer and by weed competition, especially during the first years after establishment. The negative impact of these factors can be mitigated through environmentally friendly and cost-effective techniques which favour root development. This study describes the results of innovative weeding techniques in a reforestation carried out in a former agricultural field in Solsona, NE Spain, under Continental Mediterranean Sub-humid climate conditions. The tested weeding techniques included both novel groundcovers (based on prototypes built on a new biodegradable biopolymer, jute treated with resin and recycled rubber and reference techniques, i.e. herbicide application and polyethylene and commercial biofilm groundcovers. We studied the response of hybrid walnut (Juglans x intermedia to the application of these techniques during the first vegetative period in terms of survival, aerial growth and aboveground and belowground biomass allocation. The innovative groundcovers resulted generally in similar outcomes as the reference techniques with regard to tree survival and growth, and to better results in the case of belowground and, to a lesser extent, total tree biomass. Although preliminary, our results suggest that the tested novel groundcovers, notably the model based on treated jute, represent a promising alternative to plastic mulching and herbicide application in afforestation of agricultural lands in Mediterranean continental conditions. Besides these promising productive results, the novel groundcovers bring together relevant technical and environmental benefits, related to their use (not requiring removal or being reusable and composition, based on biodegradable or recycled materials.

  18. Nutrient Effects on Belowground Organic Matter in a ...

    Science.gov (United States)

    Belowground structure and carbon dioxide emission rates were examined in minerogenic marshes of the North Inlet estuary, a system dominated by depositional processes and typical of the southeastern USA. Three areas were sampled: a long-term nutrient enrichment experiment (Goat Island); a fringing marsh that only receives drainage from an entirely forested watershed (upper Crab Haul Creek); and three locations along a creek basin that receives drainage from a residential and golf course development situated at its headwaters (Debidue Creek). Responses to fertilization at Goat Island were an increase in soil organic matter, an increase in number of rhizomes, enlarged rhizome diameters, decreased fine root mass, and increased carbon dioxide emission rates. At the Crab Haul Creek, the greatest abundances of coarse roots and rhizomes were observed in the high marsh compared to the low marsh and creekbank. The upper and mid Debidue Creek, which may be influenced by nutrient inputs associated with land development, had significantly fewer rhizomes compared to the mouth, which was dominated by exchange with bay waters. Carbon dioxide emission rates at the fertilized Goat Island plots were similar in magnitude to the upper Debidue Creek and significantly greater than the Goat Island control plots and the Crab Haul Creek. Inputs of sediment and particulates in marshes dominated by depositional processes such as the North Inlet may buffer the system from adverse effects of

  19. Performance of Planted Herbaceous Species in Longleaf Pine (Pinus palustris Mill.) Plantations: Overstory Effects of Competition and Needlefall

    Energy Technology Data Exchange (ETDEWEB)

    Dagley, C.M.

    2001-07-03

    Research to determine the separate effects of above-ground and below-ground competition and needlefall of over-story pines on under-story plant performance. Periodic monitoring of over-story crown closure, soil water content, temperature, and nutrients were conducted. Results indicate competition for light had a more determental effect on performance of herbaceous species in longleaf pine plantations than that resulting from competition for below-ground resources.

  20. Disentangling above- and below-ground competition between lianas and trees in a tropical forest

    NARCIS (Netherlands)

    Schnitzer, S.A.; Kuzee, M.E.; Bongers, F.J.J.M.

    2005-01-01

    1 Light is thought to be the most limiting resource in tropical forests, and thus aboveground competition is commonly accepted as the mechanism that structures these communities. In many tropical forests, trees compete not only with other trees, but also with lianas, which compete aggressively for

  1. Effects of canopy tree species on belowground biogeochemistry in a lowland wet tropical forest

    Science.gov (United States)

    Keller, Adrienne B.; Reed, Sasha C.; Townsend, Alan R.; Cleveland, Cory C.

    2013-01-01

    Tropical rain forests are known for their high biological diversity, but the effects of plant diversity on important ecosystem processes in this biome remain unclear. Interspecies differences in both the demand for nutrients and in foliar and litter nutrient concentrations could drive variations in both the pool sizes and fluxes of important belowground resources, yet our understanding of the effects and importance of aboveground heterogeneity on belowground biogeochemistry is poor, especially in the species-rich forests of the wet tropics. To investigate the effects of individual tree species on belowground biogeochemical processes, we used both field and laboratory studies to examine how carbon (C), nitrogen (N), and phosphorus (P) cycles vary under nine different canopy tree species – including three legume and six non-legume species – that vary in foliar nutrient concentrations in a wet tropical forest in southwestern Costa Rica. We found significant differences in belowground C, N and P cycling under different canopy tree species: total C, N and P pools in standing litter varied by species, as did total soil and microbial C and N pools. Rates of soil extracellular acid phosphatase activity also varied significantly among species and functional groups, with higher rates of phosphatase activity under legumes. In addition, across all tree species, phosphatase activity was significantly positively correlated with litter N/P ratios, suggesting a tight coupling between relative N and P inputs and resource allocation to P acquisition. Overall, our results suggest the importance of aboveground plant community composition in promoting belowground biogeochemical heterogeneity at relatively small spatial scales.

  2. Effects of belowground litter addition, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

    OpenAIRE

    Ma, L.; Guo, C.; Xin, X.; Yuan, S.; Wang, R.

    2013-01-01

    Soil carbon (C) and nitrogen (N) cycling are sensitive to changes in environmental factors and play critical roles in the responses of terrestrial ecosystems to natural and anthropogenic perturbations. This study was conducted to quantify the effects of belowground particulate litter (BPL) addition, increased precipitation and their interactions on soil C and N mineralization in two adjacent sites where belowground photosynthate allocation was manipulated through vegetation ...

  3. Invasive soil organisms and their effects on belowground processes

    Science.gov (United States)

    Erik Lilleskov; Jr. Mac A. Callaham; Richard Pouyat; Jane E. Smith; Michael Castellano; Grizelle Gonzalez; D. Jean Lodge; Rachel Arango; Frederick. Green

    2010-01-01

    Invasive species have a wide range of effects on soils and their inhabitants. By altering soils, through their direct effects on native soil organisms (including plants), and by their interaction with the aboveground environment, invasive soil organisms can have dramatic effects on the environment, the economy and human health. The most widely recognized effects...

  4. Above and belowground controls on litter decomposition in semiarid ecosystems: effects of solar radiation, water availability and litter quality

    Science.gov (United States)

    Austin, A. T.; Araujo, P. I.; Leva, P. E.; Ballare, C. L.

    2008-12-01

    The integrated controls on soil organic matter formation in arid and semiarid ecosystems are not well understood and appear to stem from a number of interacting controls affecting above- and belowground carbon turnover. While solar radiation has recently been shown to have an important direct effect on carbon loss in semiarid ecosystems as a result of photochemical mineralization of aboveground plant material, the mechanistic basis for photodegradative losses is poorly understood. In addition, there are large potential differences in major controls on above- and belowground decomposition in low rainfall ecosystems. We report on a mesocosm and field study designed to examine the relative importance of different wavelengths of solar radiation, water availability, position of senescent material above- and belowground and the importance of carbon litter quality in determining rates of abiotic and biotic decomposition. In a factorial experiment of mesocosms, we incubated leaf and root litter simultaneously above- and belowground and manipulated water availability with large and small pulses. Significant interactions between position-litter type and position-pulse sizes demonstrated interactive controls on organic mass loss. Aboveground decomposition showed no response to pulse size or litter type, as roots and leaves decomposed equally rapidly under all circumstances. In contrast, belowground decomposition was significantly altered by litter type and water pulses, with roots decomposing significantly slower and small water pulses reducing belowground decomposition. In the field site, using plastic filters which attenuated different wavelengths of natural solar radiation, we found a highly significant effect of radiation exclusion on mass loss and demonstrated that both UV-A and short-wave visible light can have important impacts on photodegradative carbon losses. The combination of position and litter quality effects on litter decomposition appear to be critical for the

  5. The relative importance of above- versus belowground competition for tree growth during early succession of a tropical moist forest

    DEFF Research Database (Denmark)

    Breugel, Michiel van; van Breugel, Paulo; Jansen, Patrick A.

    2012-01-01

    fertility in Southern Mexico, using the premise that competition for light is size-asymmetric, unlike competition for nutrients. Plant growth is thus expected to be disproportionally impeded by larger neighbors. We studied how growth and survival of 3.5-5.5 m tall saplings of Cecropia peltata...

  6. Effects of Grazing on Above- vs. Below-Ground Biomass Allocation of Alpine Grasslands on the Northern Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Chaoxu Zeng

    Full Text Available Biomass allocation is an essential concept for understanding above- vs. below-ground functions and for predicting the dynamics of community structure and ecosystem service under ongoing climate change. There is rare available knowledge of grazing effects on biomass allocation in multiple zonal alpine grassland types along climatic gradients across the Northern Tibetan Plateau. We collected the peak above- and below-ground biomass (AGB and BGB values at 106 pairs of well-matched grazed vs. fenced sites during summers of 2010-2013, of which 33 pairs were subject to meadow, 52 to steppe and 21 to desert-steppe. The aboveground net primary productivity (ANPP was represented by the peak AGB while the belowground net primary productivity (BNPP was estimated from ANPP, the ratio of living vs. dead BGB, and the root turnover rate. Two-ways analyses of variance (ANOVA and paired samples comparisons with t-test were applied to examine the effects of pasture managements (PMS, i.e., grazed vs. fenced and zonal grassland types on both ANPP and BNPP. Allometric and isometric allocation hypotheses were also tested between logarithmically transformed ANPP and BNPP using standardized major axis (SMA analyses across grazed, fenced and overall sites. In our study, a high community-dependency was observed to support the allometric biomass allocation hypothesis, in association with decreased ANPP and a decreasing-to-increasing BNPP proportions with increasing aridity across the Northern Tibetan Plateau. Grazing vs. fencing seemed to have a trivial effect on ANPP compared to the overwhelming influence of different zonal grassland types. Vegetation links above- and below-ground ecological functions through integrated meta-population adaptive strategies to the increasing severity of habitat conditions. Therefore, more detailed studies on functional diversity are essentially to achieve conservation and sustainability goals under ongoing climatic warming and intensifying

  7. Effects of Grazing on Above- vs. Below-Ground Biomass Allocation of Alpine Grasslands on the Northern Tibetan Plateau.

    Science.gov (United States)

    Zeng, Chaoxu; Wu, Jianshuang; Zhang, Xianzhou

    2015-01-01

    Biomass allocation is an essential concept for understanding above- vs. below-ground functions and for predicting the dynamics of community structure and ecosystem service under ongoing climate change. There is rare available knowledge of grazing effects on biomass allocation in multiple zonal alpine grassland types along climatic gradients across the Northern Tibetan Plateau. We collected the peak above- and below-ground biomass (AGB and BGB) values at 106 pairs of well-matched grazed vs. fenced sites during summers of 2010-2013, of which 33 pairs were subject to meadow, 52 to steppe and 21 to desert-steppe. The aboveground net primary productivity (ANPP) was represented by the peak AGB while the belowground net primary productivity (BNPP) was estimated from ANPP, the ratio of living vs. dead BGB, and the root turnover rate. Two-ways analyses of variance (ANOVA) and paired samples comparisons with t-test were applied to examine the effects of pasture managements (PMS, i.e., grazed vs. fenced) and zonal grassland types on both ANPP and BNPP. Allometric and isometric allocation hypotheses were also tested between logarithmically transformed ANPP and BNPP using standardized major axis (SMA) analyses across grazed, fenced and overall sites. In our study, a high community-dependency was observed to support the allometric biomass allocation hypothesis, in association with decreased ANPP and a decreasing-to-increasing BNPP proportions with increasing aridity across the Northern Tibetan Plateau. Grazing vs. fencing seemed to have a trivial effect on ANPP compared to the overwhelming influence of different zonal grassland types. Vegetation links above- and below-ground ecological functions through integrated meta-population adaptive strategies to the increasing severity of habitat conditions. Therefore, more detailed studies on functional diversity are essentially to achieve conservation and sustainability goals under ongoing climatic warming and intensifying human

  8. Nitrogen mediates above-ground effects of ozone but not below-ground effects in a rhizomatous sedge

    International Nuclear Information System (INIS)

    Jones, M.L.M.; Hodges, G.; Mills, G.

    2010-01-01

    Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10-30, 35-55, 60-80 and 85-105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha -1 yr -1 . Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen x ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation. - Nitrogen alters threshold of ozone-induced senescence, but not below-ground resource allocation.

  9. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive

  10. Shrub encroachment in Arctic tundra: Betula nana effects on above- and belowground litter decomposition.

    Science.gov (United States)

    McLaren, Jennie R; Buckeridge, Kate M; van de Weg, Martine J; Shaver, Gaius R; Schimel, Joshua P; Gough, Laura

    2017-05-01

    Rapid arctic vegetation change as a result of global warming includes an increase in the cover and biomass of deciduous shrubs. Increases in shrub abundance will result in a proportional increase of shrub litter in the litter community, potentially affecting carbon turnover rates in arctic ecosystems. We investigated the effects of leaf and root litter of a deciduous shrub, Betula nana, on decomposition, by examining species-specific decomposition patterns, as well as effects of Betula litter on the decomposition of other species. We conducted a 2-yr decomposition experiment in moist acidic tundra in northern Alaska, where we decomposed three tundra species (Vaccinium vitis-idaea, Rhododendron palustre, and Eriophorum vaginatum) alone and in combination with Betula litter. Decomposition patterns for leaf and root litter were determined using three different measures of decomposition (mass loss, respiration, extracellular enzyme activity). We report faster decomposition of Betula leaf litter compared to other species, with support for species differences coming from all three measures of decomposition. Mixing effects were less consistent among the measures, with negative mixing effects shown only for mass loss. In contrast, there were few species differences or mixing effects for root decomposition. Overall, we attribute longer-term litter mass loss patterns to patterns created by early decomposition processes in the first winter. We note numerous differences for species patterns between leaf and root decomposition, indicating that conclusions from leaf litter experiments should not be extrapolated to below-ground decomposition. The high decomposition rates of Betula leaf litter aboveground, and relatively similar decomposition rates of multiple species below, suggest a potential for increases in turnover in the fast-decomposing carbon pool of leaves and fine roots as the dominance of deciduous shrubs in the Arctic increases, but this outcome may be tempered by

  11. Nutrient Effects on Belowground Organic Matter in a Minerogenic Salt Marsh, North Inlet, SC

    Science.gov (United States)

    Belowground structure and carbon dioxide emission rates were examined in minerogenic marshes of the North Inlet estuary, a system dominated by depositional processes and typical of the southeastern USA. Three areas were sampled: a long-term nutrient enrichment experiment (Goat Is...

  12. Above- and belowground insect herbivores differentially affect soil nematode communities in species-rich plant communities

    NARCIS (Netherlands)

    Deyn, de G.B.; Ruijven, van J.; Raaijmakers, C.E.; Ruiter, de P.C.; Putten, van der W.H.

    2007-01-01

    Interactions between above- and belowground invertebrate herbivores alter plant diversity, however, little is known on how these effects may influence higher trophic level organisms belowground. Here we explore whether above- and belowground invertebrate herbivores which alter plant community

  13. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

    Energy Technology Data Exchange (ETDEWEB)

    Cusack, D.; Silver, W.L.; Torn, M.S.; McDowell, W.H.

    2011-04-15

    Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

  14. Luxury consumption of soil nutrients: a possible competitive strategy in above-ground and below-ground biomass allocation and root morphology for slow-growing arctic vegetation?

    NARCIS (Netherlands)

    Wijk, van M.T.; Williams, M.; Gough, L.; Hobbie, S.E.; Shaver, G.R.

    2003-01-01

    1 A field-experiment was used to determine how plant species might retain dominance in an arctic ecosystem receiving added nutrients. We both measured and modelled the above-ground and below-ground biomass allocation and root morphology of non-acidic tussock tundra near Toolik Lake, Alaska, after 4

  15. Foliar uptake of fog water and transport belowground alleviates drought effects in the cloud forest tree species, Drimys brasiliensis (Winteraceae).

    Science.gov (United States)

    Eller, Cleiton B; Lima, Aline L; Oliveira, Rafael S

    2013-07-01

    Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  16. Global climate change and above- belowground insect herbivore interactions.

    Directory of Open Access Journals (Sweden)

    Scott Wesley McKenzie

    2013-10-01

    Full Text Available Predicted changes to the Earth’s climate are likely to affect above-belowground interactions. Our understanding is limited, however, by past focus on two-species aboveground interactions mostly ignoring belowground influences. Despite their importance to ecosystem processes, there remains a dearth of empirical evidence showing how climate change will affect above-belowground interactions. The responses of above- and belowground organisms to climate change are likely to differ given the fundamentally different niches they inhabit. Yet there are few studies that address the biological and ecological reactions of belowground herbivores to environmental conditions in current and future climates. Even fewer studies investigate the consequences of climate change for above-belowground interactions between herbivores and other organisms; those that do provide no evidence of a directed response. This paper highlights the importance of considering the belowground fauna when making predictions on the effects of climate change on plant-mediated interspecific interactions.

  17. Plant neighbour identity matters to belowground interactions under controlled conditions.

    Science.gov (United States)

    Armas, Cristina; Pugnaire, Francisco Ignacio

    2011-01-01

    Root competition is an almost ubiquitous feature of plant communities with profound effects on their structure and composition. Far beyond the traditional view that plants interact mainly through resource depletion (exploitation competition), roots are known to be able to interact with their environment using a large variety of mechanisms that may inhibit or enhance access of other roots to the resource or affect plant growth (contest interactions). However, an extensive analysis on how these contest root interactions may affect species interaction abilities is almost lacking. In a common garden experiment with ten perennial plant species we forced pairs of plants of the same or different species to overlap their roots and analyzed how belowground contest interactions affected plant performance, biomass allocation patterns, and competitive abilities under abundant resource supply. Our results showed that net interaction outcome ranged from negative to positive, affecting total plant mass and allocation patterns. A species could be a strong competitor against one species, weaker against another one, and even facilitator to a third species. This leads to sets of species where competitive hierarchies may be clear but also to groups where such rankings are not, suggesting that intransitive root interactions may be crucial for species coexistence. The outcome of belowground contest interactions is strongly dependent on neighbours' identity. In natural plant communities this conditional outcome may hypothetically help species to interact in non-hierarchical and intransitive networks, which in turn might promote coexistence.

  18. Plant neighbour identity matters to belowground interactions under controlled conditions.

    Directory of Open Access Journals (Sweden)

    Cristina Armas

    Full Text Available BACKGROUND: Root competition is an almost ubiquitous feature of plant communities with profound effects on their structure and composition. Far beyond the traditional view that plants interact mainly through resource depletion (exploitation competition, roots are known to be able to interact with their environment using a large variety of mechanisms that may inhibit or enhance access of other roots to the resource or affect plant growth (contest interactions. However, an extensive analysis on how these contest root interactions may affect species interaction abilities is almost lacking. METHODOLOGY/PRINCIPAL FINDINGS: In a common garden experiment with ten perennial plant species we forced pairs of plants of the same or different species to overlap their roots and analyzed how belowground contest interactions affected plant performance, biomass allocation patterns, and competitive abilities under abundant resource supply. Our results showed that net interaction outcome ranged from negative to positive, affecting total plant mass and allocation patterns. A species could be a strong competitor against one species, weaker against another one, and even facilitator to a third species. This leads to sets of species where competitive hierarchies may be clear but also to groups where such rankings are not, suggesting that intransitive root interactions may be crucial for species coexistence. CONCLUSIONS/SIGNIFICANCE: The outcome of belowground contest interactions is strongly dependent on neighbours' identity. In natural plant communities this conditional outcome may hypothetically help species to interact in non-hierarchical and intransitive networks, which in turn might promote coexistence.

  19. Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host-parasite interactions.

    Science.gov (United States)

    Tao, Leiling; Gowler, Camden D; Ahmad, Aamina; Hunter, Mark D; de Roode, Jacobus C

    2015-10-22

    Host-parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host-parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host-parasite systems. © 2015 The Author(s).

  20. Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host–parasite interactions

    Science.gov (United States)

    Tao, Leiling; Gowler, Camden D.; Ahmad, Aamina; Hunter, Mark D.; de Roode, Jacobus C.

    2015-01-01

    Host–parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host–parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host–parasite systems. PMID:26468247

  1. Dynamic belowground ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Harris, W. F.; Santantonio, D.; McGinty, D.

    1979-01-01

    Roots comprise the primary interface between plant and soil for uptake of water and nutrients. Much is known about the biochemistry, cell physiology and membrane physics associated with these important processes. In this paper we discuss the role of the belowground ecosystem, especially the autotrophic root component, in the structure and function of forest ecosystems. Beyond recognizing roles of anchoring terrestrial plants and uptake of water and nutrients, this component of the forest has been largely neglected in an ecosystem context. In order to focus discussion on the properties of the belowground ecosystem, we use the term rhizosphere to include roots, mycorrhizae, microbes, and rhizophagus invertebrates.

  2. The Unintended Effects of Private School Competition

    DEFF Research Database (Denmark)

    Andersen, Simon Calmar; Serritzlew, Søren

    2007-01-01

    background information on more than 35,000 public school students in the Danish voucher system. This design provides a relatively firm support for the conclusion that competition does not improve achievement of public school students but that it increases public expenditure per student. Finally, we argue......We examine whether competition from private schools improves public school performance and expenditure. It is difficult methodologically to isolate the effect of competition, but we use new measures of competition in both the public and the private school sector and a data set comprising detailed...

  3. Effects of manipulated above- and belowground organic matter input on soil respiration in a Chinese pine plantation.

    Science.gov (United States)

    Fan, Juan; Wang, Jinsong; Zhao, Bo; Wu, Lianhai; Zhang, Chunyu; Zhao, Xiuhai; Gadow, Klaus V

    2015-01-01

    Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis) plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT), only litter removal (LR), control (CK), only root trenching (RT) and litter addition (LA). We found that either aboveground litter removal or root trenching decreased soil respiration. On average, soil respiration rate was significantly decreased in the LRRT treatment, by about 38.93% ± 2.01% compared to the control. Soil respiration rate in the LR treatment was 30.65% ± 1.87% and in the RT treatment 17.65% ± 1.95% lower than in the control. Litter addition significantly increased soil respiration rate by about 25.82% ± 2.44% compared to the control. Soil temperature and soil moisture were the main factors affecting seasonal variation in soil respiration. Up to the 59.7% to 82.9% seasonal variation in soil respiration is explained by integrating soil temperature and soil moisture within each of the various organic matter treatments. The temperature sensitivity parameter, Q10, was higher in the RT (2.72) and LA (3.19) treatments relative to the control (2.51), but lower in the LRRT (1.52) and LR treatments (1.36). Our data suggest that manipulation of soil organic matter input can not only alter soil CO2 efflux, but also have profound effect on the temperature sensitivity of organic carbon decomposition in a temperate pine forest.

  4. Effects of intrapopulation competition on morphological and ...

    African Journals Online (AJOL)

    Effects of intrapopulation competition on morphological and agronomic characters of Jute plant ( Corchorus olitorius L.) ... There was a gradual decline in all attributes except height/plant as population density increased. These observations confirmed the occurrence of intraspecific competition in population of jute plant.

  5. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

    Science.gov (United States)

    Daniela F. Cusack; Whendee L. Silver; Margaret S. Torn; William H. McDowell

    2011-01-01

    Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and...

  6. Effects of belowground biota on primary and secondary metabolites in Brassica oleracea

    NARCIS (Netherlands)

    Wurst, S.; Langel, R.; Rodger, S.; Scheu, S.

    2006-01-01

    Soil organisms in direct and indirect interaction with plant roots affect aboveground herbivores, likely by inducing different plant responses. We investigated the combined effects of the root-knot nematode Meloidogyne incognita (in direct interaction with roots) and the endogeic earthworm

  7. Identifying qualitative effects of different grazing types on below-ground communities and function in a long-term field experiment

    DEFF Research Database (Denmark)

    Macdonald, Catriona A.; Crawley, Michael J.; Wright, Denis J.

    2015-01-01

    for ecosystem functions. The mechanism behind these impacts are likely to be driven by both direct effects of grazing altering the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude...... invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi-trophic interactions between above- and below-ground communities....

  8. Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root / shoot herbivores

    Directory of Open Access Journals (Sweden)

    James Michael William Ryalls

    2013-11-01

    Full Text Available Interactions between above- and belowground herbivores have been prominent in the field of aboveground-belowground ecology from the outset, although little is known about how climate change affects these organisms when they share the same plant. Additionally, the interactive effects of multiple factors associated with climate change such as elevated temperature (eT and elevated atmospheric carbon dioxide (eCO2 are untested. We investigated how eT and eCO2 affected larval development of the lucerne weevil (Sitona discoideus and colonisation by the pea aphid (Acyrthosiphon pisum, on three cultivars of a common host plant, lucerne (Medicago sativa. Sitona discoideus larvae feed on root nodules housing N2-fixing rhizobial bacteria, allowing us to test the effects of eT and eCO2 on three trophic levels. Moreover, we assessed the influence of these factors on plant growth. eT increased plant growth rate initially (6, 8 and 10 weeks after sowing, with cultivar ‘Sequel’ achieving the greatest height. Inoculation with aphids, however, reduced plant growth at week 14. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation by 56%, but only at ambient temperatures. Weevil presence increased net root biomass and nodulation, by 31 and 45%, respectively, showing an overcompensatory plant growth response. Effects of eT and eCO2 on root nodulation were mirrored by weevil larval development; eT and eCO2 reduced and increased larval development, respectively. Contrary to expectations, aphid colonisation was unaffected by eT or eCO2, but there was a near-significant 10% reduction in colonisation rates on plants with weevils present belowground. The contrasting effects of eT and eCO2 on weevils potentially occurred through changes in root nodulation patterns.

  9. Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root/shoot herbivores.

    Science.gov (United States)

    Ryalls, James M W; Riegler, Markus; Moore, Ben D; Lopaticki, Goran; Johnson, Scott N

    2013-01-01

    Interactions between above- and belowground herbivores have been prominent in the field of aboveground-belowground ecology from the outset, although little is known about how climate change affects these organisms when they share the same plant. Additionally, the interactive effects of multiple factors associated with climate change such as elevated temperature (eT) and elevated atmospheric carbon dioxide (eCO2) are untested. We investigated how eT and eCO2 affected larval development of the lucerne weevil (Sitona discoideus) and colonization by the pea aphid (Acyrthosiphon pisum), on three cultivars of a common host plant, lucerne (Medicago sativa). Sitona discoideus larvae feed on root nodules housing N2-fixing rhizobial bacteria, allowing us to test the effects of eT and eCO2 across trophic levels. Moreover, we assessed the influence of these factors on plant growth. eT increased plant growth rate initially (6, 8 and 10 weeks after sowing), with cultivar "Sequel" achieving the greatest height. Inoculation with aphids, however, reduced plant growth at week 14. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation by 56%, but only at ambient temperatures. Weevil presence increased net root biomass and nodulation, by 31 and 45%, respectively, showing an overcompensatory plant growth response. Effects of eT and eCO2 on root nodulation were mirrored by weevil larval development; eT and eCO2 reduced and increased larval development, respectively. Contrary to expectations, aphid colonization was unaffected by eT or eCO2, but there was a near-significant 10% reduction in colonization rates on plants with weevils present belowground. The contrasting effects of eT and eCO2 on weevils potentially occurred through changes in root nodulation patterns.

  10. Competition effects in an afrotemperate forest

    Directory of Open Access Journals (Sweden)

    Thomas Seifert

    2014-09-01

    Full Text Available Background Information about competition responses is mainly available for monospecific stands or mixed stands with a small number of species. Studies on complex multi-species and highly structured forest ecosystems are scarce. Accordingly, the objective of this study was to quantify competition effects and analyse competition responses in a species-diverse afrotemperate forest in South Africa, based on an observational study with mapped tree positions and long-term diameter increment records. Methods The sensitivity to competition was analysed for individual species and involved the calculation of the slope of the linear relation between the value of a competition index (CI and diameter growth as a measure of sensitivity. In a next step different competition indices were combined and tree diameters were grouped in three classes as surrogates for canopy status and ontogenetic stage. Results Five competition indices were found to be effective in showing sensitivity to competition for a number of canopy and sub-canopy species. Significant linear regressions were fitted for 18 of a total of 25 species. Species reactions varied significantly in their sensitivity to the different CIs. The indices were classified as belonging to two groups, those that responded more to local crowding and those that are more sensitive to overtopping, which revealed species-specific sensitivities to both factors. The analysis based on diameter classes revealed that species clearly changed their sensitivity to crowding or overtopping depending on diameter. Canopy and sub-canopy species showed distinct differences in their reactions. Conclusions The application of multiple CIs brought novel insights relating to the dynamics of afrotemperate forests. The response patterns to different competition indices that focus on crowding and overtopping are varied and tree diameter dependent, indicating that oversimplified assumptions are not warranted in the interpretation of CI

  11. Grass-on-grass competition along a catenal gradient in mesic ...

    African Journals Online (AJOL)

    Three aboveground treatments (full light competition, no light competition and clipping to simulate grazing), and two belowground treatments (full belowground competition and belowground competition excluded by a root tube), were used. On all soil depths the three grass species differed in mean mass, with E. racemosa ...

  12. PLACEBO EFFECTS IN COMPETITIVE SPORT: QUALITATIVE DATA

    Directory of Open Access Journals (Sweden)

    Christopher J. Beedie

    2007-03-01

    Full Text Available The paper examines the placebo effect in sports performance. The possibility that the placebo effect is a more common phenomenon than the quantity of published research would suggest is briefly addressed. It is suggested that the placebo control design often used in sports performance research masks any placebo effects and thus presents a false picture of the mechanisms underlying performance-enhancing interventions in the real world. An electronic survey was sent to 48 competitive, international and professional athletes. Questions related to the placebo effect in competitive sport. Thirty responses were received. Data indicate that the majority (97% of respondents believe that the placebo effect can exert an influence on sports performance, and that a significant number (73% have experienced what they defined as a placebo effect. Inductive content analysis reveals that these experiences fall into several categories such as explicit placebo effects, inadvertent false beliefs, ritual and reverse placebo effects. Furthermore, 10 respondents (33% offer explanations as to the nature of the placebo effect. Again, inductive content analysis reveals that these explanations fall into several categories including deliberate changes in competitive strategy, belief/expectancy, faith in a third party, and marketing. Overall, responses support previous experimental research and anecdotal reports that have found a relationship between belief and sports performance. It is suggested that further research be structured to not simply control for the placebo effect, but to elucidate it

  13. Eliciting maize defense pathways aboveground attracts belowground biocontrol agents

    Science.gov (United States)

    Filgueiras, Camila Cramer; Willett, Denis S.; Pereira, Ramom Vasconcelos; Moino Junior, Alcides; Pareja, Martin; Duncan, Larry W.

    2016-01-01

    Plant defense pathways mediate multitrophic interactions above and belowground. Understanding the effects of these pathways on pests and natural enemies above and belowground holds great potential for designing effective control strategies. Here we investigate the effects of aboveground stimulation of plant defense pathways on the interactions between corn, the aboveground herbivore adult Diabrotica speciosa, the belowground herbivore larval D. speciosa, and the subterranean ento-mopathogenic nematode natural enemy Heterorhabditis amazonensis. We show that adult D. speciosa recruit to aboveground herbivory and methyl salicylate treatment, that larval D. speciosa are relatively indiscriminate, and that H. amazonensis en-tomopathogenic nematodes recruit to corn fed upon by adult D. speciosa. These results suggest that entomopathogenicnematodes belowground can be highly attuned to changes in the aboveground parts of plants and that biological control can be enhanced with induced plant defense in this and similar systems. PMID:27811992

  14. Competitive Aggression without Interaction: Effects of Competitive versus Cooperative Instructions on Aggressive Behavior in Video Games.

    Science.gov (United States)

    Anderson, Craig A.; Morrow, Melissa

    1995-01-01

    Extended and tested Deutsch's theory of competition effects. Predicted that people view competitive situations as inherently more aggressive than cooperative ones. Predicted that leading people to think of an aggressive situation in competitive terms would increase aggressive behavior. Increase of kill ratio occurred in absence of changes in…

  15. Exposure Order Effects and Advertising Competition

    OpenAIRE

    Oksana Loginova

    2008-01-01

    This paper applies the theories of exposure order effects, developed in the psychology literature, to an industrial organization model to explore their role in advertising competition. There are two firms and infinitely many identical consumers. The firms produce a homogeneous product and distribute their brands through a common retailer. Consumers randomly arrive at the retailer and buy their most preferred brands. The order in which a consumer sees the advertising messages affects his brand...

  16. Empirical and theoretical challenges in aboveground-belowground ecology

    DEFF Research Database (Denmark)

    W.H. van der Putten,; R.D. Bardgett; P.C. de Ruiter

    2009-01-01

    from an empirical perspective and in specific ecological settings or contexts. Belowground interactions operate at different spatial and temporal scales. Due to the relatively low mobility and high survival of organisms in the soil, plants have longer lasting legacy effects belowground than aboveground....... Our current challenge is to understand how aboveground-belowground biotic interactions operate across spatial and temporal scales, and how they depend on, as well as influence, the abiotic environment. Because empirical capacities are too limited to explore all possible combinations of interactions...... and environmental settings, we explore where and how they can be supported by theoretical approaches to develop testable predictions and to generalise empirical results. We review four key areas where a combined aboveground-belowground approach offers perspectives for enhancing ecological understanding, namely...

  17. Brand effect versus competitiveness in hypernetworks.

    Science.gov (United States)

    Guo, Jin-Li; Suo, Qi

    2015-02-01

    A few of evolving models in hypernetworks have been proposed based on uniform growth. In order to better depict the growth mechanism and competitive aspect of real hypernetworks, we propose a model in term of the non-uniform growth. Besides hyperdegrees, the other two important factors are introduced to underlie preferential attachment. One dimension is the brand effect and the other is the competitiveness. Our model can accurately describe the evolution of real hypernetworks. The paper analyzes the model and calculates the stationary average hyperdegree distribution of the hypernetwork by using Poisson process theory and a continuous technique. We also address the limit in which this model has a condensation. The theoretical analyses agree with numerical simulations. Our model is universal, in that the standard preferential attachment, the fitness model in complex networks and scale-free model in hypernetworks can all be seen as degenerate cases of the model.

  18. Brand effect versus competitiveness in hypernetworks

    Science.gov (United States)

    Guo, Jin-Li; Suo, Qi

    2015-02-01

    A few of evolving models in hypernetworks have been proposed based on uniform growth. In order to better depict the growth mechanism and competitive aspect of real hypernetworks, we propose a model in term of the non-uniform growth. Besides hyperdegrees, the other two important factors are introduced to underlie preferential attachment. One dimension is the brand effect and the other is the competitiveness. Our model can accurately describe the evolution of real hypernetworks. The paper analyzes the model and calculates the stationary average hyperdegree distribution of the hypernetwork by using Poisson process theory and a continuous technique. We also address the limit in which this model has a condensation. The theoretical analyses agree with numerical simulations. Our model is universal, in that the standard preferential attachment, the fitness model in complex networks and scale-free model in hypernetworks can all be seen as degenerate cases of the model.

  19. The effects of intransitive competition on coexistence.

    Science.gov (United States)

    Gallien, Laure; Zimmermann, Niklaus E; Levine, Jonathan M; Adler, Peter B

    2017-07-01

    Coexistence theory has been developed with an almost exclusive focus on interactions between two species, often ignoring more complex and indirect interactions, such as intransitive loops, that can emerge in competition networks. In fact, intransitive competition has typically been studied in isolation from other pairwise stabilising processes, and thus little is known about how intransitivity interacts with more traditional drivers of species coexistence such as niche partitioning. To integrate intransitivity into traditional coexistence theory, we developed a metric of growth rate when rare, Δri¯, to identify and quantify the impact of intransitive competition against a backdrop of pairwise stabilising niche differences. Using this index with simulations of community dynamics, we demonstrate that intransitive loops can both stabilise or destabilise species coexistence, but the strength and importance of intransitive interactions are significantly affected by the length and the topology of these loops. We conclude by showing how Δri¯ can be used to evaluate effects of intransitivity in empirical studies. Our results emphasise the need to integrate complex mechanisms emerging from diverse interactions into our understanding of species coexistence. © 2017 John Wiley & Sons Ltd/CNRS.

  20. The effect of belowground herbivory by wireworms (Coleoptera: Elateridae) on performance of Calamagrostis epigejos (L) Roth in post-mining sites

    Czech Academy of Sciences Publication Activity Database

    Roubíčková, A.; Mudrák, Ondřej; Frouz, J.

    2012-01-01

    Roč. 50, č. 1 (2012), s. 51-55 ISSN 1164-5563 Institutional support: RVO:67985939 Keywords : Belowground herbivory * Wireworms * Calamagrostis epigejos Subject RIV: EH - Ecology, Behaviour Impact factor: 1.838, year: 2012

  1. Intraspecific competition reveals conditional fitness effects of single gene polymorphism at the Arabidopsis root growth regulator BRX.

    Science.gov (United States)

    Shindo, Chikako; Bernasconi, Giorgina; Hardtke, Christian S

    2008-01-01

    Intraspecific genetic variation for morphological traits is observed in many organisms. In Arabidopsis thaliana, alleles responsible for intraspecific morphological variation are increasingly being identified. However, the fitness consequences remain unclear in most cases. Here, the fitness effects of alleles of the BRX gene are investigated. A brx loss-of-function allele, which was found in a natural accession, results in a highly branched but poorly elongated root system. Comparison between the control accession Sav-0 and an introgression of brx into this background (brxS) indicated that, surprisingly, brx loss of function did not negatively affect fitness in pure stands. However, in mixed, well-watered stands brxS performance and reproductive output decreased significantly, as the proportion of Sav-0 neighbors increased. Additional comparisons between brxS and a brxS line that was complemented by a BRX transgene confirmed a direct effect of the loss-of-function allele on plant performance, as indicated by restored competitive ability of the transgenic genotype. Further, because plant height was very similar across genotypes and because the experimental setup largely excluded shading effects, the impaired competitiveness of the brx loss-of-function genotype likely reflects below-ground competition. In summary, these data reveal conditional fitness effects of a single gene polymorphism in response to intraspecific competition in Arabidopsis.

  2. Interspecific Resource Competition Effects on Fisheres Revenue

    NARCIS (Netherlands)

    Wolfshaar, van de K.E.; Schellekens, T.; Poos, J.J.; Kooten, van T.

    2012-01-01

    In many fisheries multiple species are simultaneously caught while stock assessments and fishing quota are defined at species level. Yet species caught together often share habitat and resources, resulting in interspecific resource competition. The consequences of resource competition on population

  3. 47 CFR 76.906 - Presumption of no effective competition.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Presumption of no effective competition. 76.906... competition. In the absence of a demonstration to the contrary, cable systems are presumed not to be subject to effective competition. ...

  4. Effects of temperature on intraspecific competition in ectotherms.

    Science.gov (United States)

    Amarasekare, Priyanga; Coutinho, Renato M

    2014-09-01

    Understanding how temperature influences population regulation through its effects on intraspecific competition is an important question for which there is currently little theory or data. Here we develop a theoretical framework for elucidating temperature effects on competition that integrates mechanistic descriptions of life-history trait responses to temperature with population models that realistically capture the variable developmental delays that characterize ectotherm life cycles. This framework yields testable comparative predictions about how intraspecific competition affects reproduction, development, and mortality under alternative hypotheses about the temperature dependence of competition. The key finding is that ectotherm population regulation in seasonal environments depends crucially on the mechanisms by which temperature affects competition. When competition is strongest at temperatures optimal for reproduction, effects of temperature and competition act antagonistically, leading to more complex dynamics than when competition is temperature independent. When the strength of competition increases with temperature past the optimal temperature for reproduction, effects of temperature and competition act synergistically, leading to dynamics qualitatively similar to those when competition is temperature independent. Paradoxically, antagonistic effects yield a higher population floor despite greater fluctuations. These findings have important implications for predicting effects of climate warming on population regulation. Synergistic effects of temperature and competition can predispose populations to stochastic extinction by lowering minimum population sizes, while antagonistic effects can increase the potential for population outbreaks through greater fluctuations in abundance.

  5. Belowground herbivory and plant defenses

    NARCIS (Netherlands)

    Van Dam, N.M.

    2009-01-01

    Belowground-feeding herbivores may be very destructive to plants. Roots are known to produce various defense compounds to protect themselves against these herbivores, both with direct and indirect—inducible—defense compounds. Recent literature reviews reveal no overall pattern for root-shoot defense

  6. The effects of nurse staffing on hospital financial performance: competitive versus less competitive markets.

    Science.gov (United States)

    Everhart, Damian; Neff, Donna; Al-Amin, Mona; Nogle, June; Weech-Maldonado, Robert

    2013-01-01

    Hospitals facing financial uncertainty have sought to reduce nurse staffing as a way to increase profitability. However, nurse staffing has been found to be important in terms of quality of patient care and nursing-related outcomes. Nurse staffing can provide a competitive advantage to hospitals and as a result of better financial performance, particularly in more competitive markets. In this study, we build on the Resource-Based View of the Firm to determine the effect of nurse staffing on total profit margin in more competitive and less competitive hospital markets in Florida. By combining a Florida statewide nursing survey with the American Hospital Association Annual Survey and the Area Resource File, three separate multivariate linear regression models were conducted to determine the effect of nurse staffing on financial performance while accounting for market competitiveness. The analysis was limited to acute care hospitals. Nurse staffing levels had a positive association with financial performance (β = 3.3, p = .02) in competitive hospital markets, but no significant association was found in less competitive hospital markets. Hospitals in more competitive hospital markets should reconsider reducing nursing staff, as these cost-cutting measures may be inefficient and negatively affect financial performance.

  7. Competition

    CERN Document Server

    Staff Association

    2016-01-01

      The Staff Association is organising a competition from 13 to 21 December 2016. There are several Go Sport vouchers to win with a value of 50 € each. Try your luck! To participate, you just have to be a member of the Staff Association and take the online quiz: https://ap-vote.web.cern.ch/content/jeu-concours-de-noel. The winners will be drawn among the correct answers.

  8. Competition

    CERN Document Server

    Staff Association

    2016-01-01

      The Staff Association is organising a competition from April 11 to 20. There are several Go Sport gift vouchers with a value of 50 € each to win. Try your luck! To participate, you just have to be a member of the Staff Association and take the online quiz: https://ap-vote.web.cern.ch/content/jeu-concours. The winners will be drawn among the correct answers.

  9. Competition

    CERN Multimedia

    Staff Association

    2017-01-01

    Get ready for the Easter Egg Hunt! The Staff Association is organising a competition from 10 to 21 April 2017. There are several Go Sport gift vouchers to win, with a value of 50 € each. Try your luck! Count the number of different eggs that we have hidden on our website. Then indicate your answer in the online form. To participate, you just need to be a member of the Staff Association. Winners will be randomly drawn among the correct answers.

  10. No consistent effect of plant species richness on resistance to simulated climate change for above- or below-ground processes in managed grasslands.

    Science.gov (United States)

    Dormann, Carsten F; von Riedmatten, Lars; Scherer-Lorenzen, Michael

    2017-06-17

    Species richness affects processes and functions in many ecosystems. Since management of temperate grasslands is directly affecting species composition and richness, it can indirectly govern how systems respond to fluctuations in environmental conditions. Our aim in this study was to investigate whether species richness in managed grasslands can buffer the effects of drought and warming manipulations and hence increase the resistance to climate change. We established 45 plots in three regions across Germany, each with three different management regimes (pasture, meadow and mown pasture). We manipulated spring warming using open-top chambers and summer drought using rain-out shelters for 4 weeks. Measurements of species richness, above- and below-ground biomass and soil carbon and nitrogen concentrations showed significant but inconsistent differences among regions, managements and manipulations. We detected a three-way interaction between species richness, management and region, indicating that our study design was sensitive enough to detect even intricate effects. We could not detect a pervasive effect of species richness on biomass differences between treatments and controls, indicating that a combination of spring warming and summer drought effects on grassland systems are not consistently moderated by species richness. We attribute this to the relatively high number of species even at low richness levels, which already provides the complementarity required for positive biodiversity-ecosystem functioning relationships. A review of the literature also indicates that climate manipulations largely fail to show richness-buffering, while natural experiments do, suggesting that such manipulations are milder than reality or incur treatment artefacts.

  11. Effects of Plant Density and Water Stress on Competitive Ability and Yield of Medicago Sativa L. and Bromus tomentellus Boiss.in Mono and Mixed Cropping

    Directory of Open Access Journals (Sweden)

    S. Barati

    2016-03-01

    Full Text Available The effects of plant density and water stress on yield of Medicago sativa and Bromus tomentellus was studied. A greenhouse experiment was conducted at Isfahan University of Technology in 2013. The experiment included 18 treatments, three crop compositions (M.sativa, B. tomentellus or mixture of the two, two plant density levels, three watering regimes and four replicates, arranged in a completely randomized block design. Results showed that total yield of M. sativa mono-cropping was higher than mixed cropping and it was higher than B. tomentellus mono-cropping. Land Equivalent Ratio (LER values were less than 1 for all mixed cropping treatments, indicated the interspecific competition in mixed cropping. The biomass production per plant decreased with increasing density, competition for resource utilization and water stress. Compare of above-ground and below-ground dry matter showed that M. sativa appeared to be more constrained by intraspecific than by interspecific competition, Conversely, B. tomentellus was more suppressed by interspecific competition exerted by M. sativa than by intraspecific competition. Relative competition intensity (RCI values were positive for B. tomentellus and negative for M.sativa, implying that competitive ability of M.sativa was higher than B. tomentellus in mixed cropping .

  12. The effects of arbuscular mycorrhizal fungi and root interaction on the competition between Trifolium repens and Lolium perenne

    Directory of Open Access Journals (Sweden)

    Haiyan Ren

    2017-12-01

    Full Text Available Understanding the factors that alter competitive interactions and coexistence between plants is a key issue in ecological research. A pot experiment was conducted to test the effects of root interaction and arbuscular mycorrhizal fungi (AMF inoculation on the interspecies competition between Trifolium repens and Lolium perenne under different proportions of mixed sowing by the combination treatment of two levels of AMF inoculation (inoculation and non-inoculation and two levels of root interaction (root interaction and non-root interaction. Overall, the aboveground and belowground biomass of T. repens and L. perenne were not altered by AMF inoculation across planting ratios, probably because the fertile soil reduced the positive effect of AMF on plant growth. Both inter- and intraspecies root interaction significantly decreased the aboveground biomass of T. repens, but tended to increase the aboveground biomass of L. perenne across planting ratios, and thus peaked at the 4:4 polyculture. These results showed that T. repens competed poorly with L. perenne because of inter and intraspecies root interaction. Our results indicate that interspecies root interaction regulates the competitive ability of grass L. perenne and legume T. repens in mixtures and further makes great contribution for overyielding. Furthermore, AMF may not be involved in plant–plant interaction in fertile condition.

  13. Interactions between above- and belowground organisms modified in climate change experiments

    DEFF Research Database (Denmark)

    Stevnsbak, Karen; Scherber, Christoph; Gladbach, David

    2012-01-01

    a reduction in herbivory and cascading effects through the soil food web. Interactions between CO2, drought and warming can affect belowground protozoan abundance. Our findings imply that climate change affects aboveground–belowground interactions through changes in nutrient availability.......Climate change has been shown to affect ecosystem process rates and community composition, with direct and indirect effects on belowground food webs. In particular, altered rates of herbivory under future climate4 can be expected to influence above–belowground interactions. Here, we use...... to experimentally increase aboveground herbivory in grass phytometers exposed to all eight combinations of climate change factors for three years. Aboveground herbivory increased the abundance of belowground protozoans, microbial growth and microbial nitrogen availability. Increased CO2 modified these links through...

  14. Competition between magnetic catalysis effect and chiral rotation effect

    Science.gov (United States)

    Wang, Lingxiao; Cao, Gaoqing

    2018-02-01

    In this work, we explore the competition between magnetic catalysis effect and chiral rotation effect in a general parallel electromagnetic field within the effective Nambu-Jona-Lasinio model. For a given electric field E at zero temperature, the mass gap shows three different features with respect to an increasing magnetic field B : increasing monotonically, decreasing after increasing, and decreasing monotonically. By making use of strong magnetic field approximation, we illuminate that this is due to the competition between catalysis effect and chiral rotation effect induced both by the magnetic field, and a critical electric field √{e Ec }=86.4 MeV is found beyond which the mass gap will eventually decrease at large B . As only large magnetic field is relevant for the derivation, the critical electric field does not depend on the temperature T or chemical potential μ .

  15. An Effective System of Sports Competition Management

    Directory of Open Access Journals (Sweden)

    Roman Szostek

    2011-01-01

    Full Text Available An innovatory system of managing sports competitions has been presented. Its advantages with regard to other currently used systems are discussed. A theorem connected with such a system has been presented in the last section of the paper. Sports competitions aim to establish a ranking of the participating teams. This consists of sorting teams according to a quality which can be thought of as the ability to win matches. Direct measurement of this quality is not possible, since the ability to win matches depends on a great variety of factors being difficult to determine. Nevertheless, it is possible to compare any two teams if they play a match. These matches are played under normal rules. In turn, all the rules valid during sports competitions, outside the matches, make a system of sport competition. Sorting sports teams differs from typical problems of sorting. The result of a comparison of teams is sometimes misleading. It happens that a team with a greater ability to win matches loses a match to a team with a smaller ability to win matches. Thus, the problem of sorting teams is a probabilistic problem. Due to this reason, traditional sorting methods are ineffective in terms of managing sports competitions. (original abstract

  16. Above- and below-ground effects of plant diversity depend on species origin: an experimental test with multiple invaders.

    Science.gov (United States)

    Kuebbing, Sara E; Classen, Aimée T; Sanders, Nathan J; Simberloff, Daniel

    2015-11-01

    Although many plant communities are invaded by multiple nonnative species, we have limited information on how a species' origin affects ecosystem function. We tested how differences in species richness and origin affect productivity and seedling establishment. We created phylogenetically paired native and nonnative plant communities in a glasshouse experiment to test diversity-productivity relationships and responsible mechanisms (i.e. selection or complementarity effects). Additionally, we tested how productivity and associated mechanisms influenced seedling establishment. We used diversity-interaction models to describe how species' interactions influenced diversity-productivity relationships. Communities with more species had higher total biomass than did monoculture communities, but native and nonnative communities diverged in root : shoot ratios and the mechanism responsible for increased productivity: positive selection effect in nonnative communities and positive complementarity effect in native communities. Seedling establishment was 46% lower in nonnative than in native communities and was correlated with the average selection effect. Interspecific interactions contributed to productivity patterns, but the specific types of interactions differed between native and nonnative communities. These results reinforce findings that the diversity-productivity mechanisms in native and nonnative communities differ and are the first to show that these mechanisms can influence seedling establishment and that different types of interactions influence diversity-productivity relationships. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  17. Nitrogen Over-enrichment Effects on Belowground Structure in Coastal Wetlands and Implications for Delivery of Ecosysytem Services

    Science.gov (United States)

    Salt marshes supply many ecosystem services, such as fish, crab and bird habitat, flood abatement and carbon sequestration. Since salt marshes function as a moderating buffer between ocean and land, they are one of the first lines of defense to absorb the effects of sea level ris...

  18. Closing the Knowledge Gap: Effects of Land Use Conversion on Belowground Carbon near the 100th Meridian

    Science.gov (United States)

    Waldron, S. E.; Phillips, R. L.; Dell, R.; Suddick, E. C.

    2012-12-01

    Native prairie of the northern Great Plains near the 100th meridian is currently under land use conversion pressure due to high commodity prices. From 2002 to 2007, approximately 303,515 hectares of prairie were converted to crop production in the Prairie Pothole Region (PPR) from Montana to the Dakotas. The spatiotemporal effects of land-use conversion on soil organic matter are still unclear for the PPR. Effects will vary with management, soil properties and time, making regional experiments and simulation modeling necessary. Grassland conservationists are interested in soil carbon data and soil carbon simulation models to inform potential voluntary carbon credit programs. These programs require quantification of changes in soil carbon associated with land-use conversion and management. We addressed this issue by 1) designing a regional-scale experiment, 2) collecting and analyzing soil data, and 3) interviewing producers about land management practices, as required for regional, process-based biogeochemical models. We selected farms at random within a 29,000 km2 area of interest and measured soil properties at multiple depths for native prairie and adjacent annual crop fields. The cores were processed at six different depths (between 0 and 100 cm) for bulk density, pH, texture, total carbon, inorganic carbon, and total nitrogen. We found that the largest difference in soil organic carbon occurred at the 0-10 cm depth, but the magnitude of the effect of land use varied with soil properties and land management. Results from this project, coupled with regional model simulations (Denitrification-Decomposition, DNDC) represent the baseline data needed for future voluntary carbon credit programs and long-term carbon monitoring networks. Enrollment in such programs could help ranchers and farmers realize a new income stream from maintaining their native prairie and the carbon stored beneath it.

  19. Intraspecific competition increases toxicant effects in outdoor pond microcosms.

    Science.gov (United States)

    Knillmann, Saskia; Stampfli, Nathalie C; Beketov, Mikhail A; Liess, Matthias

    2012-10-01

    Competition is a ubiquitous factor in natural populations and has been reported to alter the ecological impact of xenobiotics. We investigated conditions that mirror the natural variation of environmental factors. For this, different treatments were applied to 96 outdoor pond microcosms by shading the ponds and harvesting the communities. Then, the effect of esfenvalerate (0.03, 0.3, and 3 μg/L) on populations of Daphnia spp. was investigated. The pesticide effect and the sensitivity of Daphnia spp. in the context of a zooplankton community was increased by intraspecific competition 11 days after contamination. This relationship was most pronounced at 0.03 and 0.3 μg/L esfenvalerate, which were the concentrations that led to partial mortality. In contrast, interspecific interaction did not significantly alter the effect of the toxicant on Daphnia spp. Modelled concentration-response curves showed that the negative effects of the pesticide differed by a factor of up to 100 depending on the strength of intraspecific competition. In addition, a wider range of concentrations led to negative effects at high levels of intraspecific competition than at low levels. We argue that increased intraspecific competition reduces the availability of resources at the individual level and thereby increases the effect of contaminants. This knowledge about the interaction between competition and the response to toxicants is important in assessing the effects of these factors under field conditions.

  20. Evaluating the effectiveness of mulch application to store carbon belowground: Short-term effects of mulch application on soluble soil and microbial C and N in agricultural soils with low and high organic matter

    Science.gov (United States)

    Chen, Janet; Heiling, Maria; Resch, Christian; Gruber, Roman; Dercon, Gerd

    2017-04-01

    Agricultural soils have the potential to contain a large pool of carbon and, depending on the farming techniques applied, can either effectively store carbon belowground, or further release carbon, in the form of CO2, into the atmosphere. Farming techniques, such as mulch application, are frequently proposed to increase carbon content belowground and improve soil quality and can be used in efforts to reduce greenhouse gas levels, such as in the "4 per 1000" Initiative. To test the effectiveness of mulch application to store carbon belowground in the short term and improve soil nutrient quality, we maintained agricultural soils with low and high organic carbon content (disturbed top soil from local Cambisols and Chernozems) in greenhouse mesocosms (70 cm deep with a radius of 25 cm) with controlled moisture for 4 years. Over the 4 years, maize and soybean were grown yearly in rotation and mulch was removed or applied to soils once plant material was harvested at 2 ton/ha dry matter. In addition, soil disturbance was kept to a minimum, with only surface disturbance of a few centimeters to keep soil free from weeds. After 4 years, we measured effects of mulch application on soluble soil and microbial carbon and nitrogen in the mesocosms and compared effects of mulch application versus no mulch on soils from 0-5 cm and 5-15 cm with low and high organic matter. We predicted that mulch would increase soil carbon and nitrogen content and mulch application would have a greater effect on soils with low organic matter than soils with high organic matter. In soils with low organic carbon content and larger predicted potential to increase soil carbon, mulch application did not increase soluble soil or microbial carbon or nitrogen compared to the treatments without mulch application. However, mulch application significantly increased the δ13C of both microbial and soluble soil carbon in these soils by 1 ‰ each, indicating a shift in belowground processes, such as increased

  1. The effects of competition on medical service provision.

    Science.gov (United States)

    Brosig-Koch, Jeannette; Hehenkamp, Burkhard; Kokot, Johanna

    2017-12-01

    We explore how competition between physicians affects medical service provision. Previous research has shown that, without competition, physicians deviate from patient-optimal treatment under payment systems like capitation and fee-for-service. Although competition might reduce these distortions, physicians usually interact with each other repeatedly over time and only a fraction of patients switches providers at all. Both patterns might prevent competition to work in the desired direction. To analyze the behavioral effects of competition, we develop a theoretical benchmark that is then tested in a controlled laboratory experiment. Experimental conditions vary physician payment and patient characteristics. Real patients benefit from provision decisions made in the experiment. Our results reveal that, in line with the theoretical prediction, introducing competition can reduce overprovision and underprovision, respectively. The observed effects depend on patient characteristics and the payment system, though. Tacit collusion is observed and particularly pronounced with fee-for-service payment, but it appears to be less frequent than in related experimental research on price competition. Copyright © 2017 John Wiley & Sons, Ltd.

  2. The links between ecosystem multifunctionality and above- and belowground biodiversity are mediated by climate

    Science.gov (United States)

    Jing, Xin; Sanders, Nathan J.; Shi, Yu; Chu, Haiyan; Classen, Aimée T.; Zhao, Ke; Chen, Litong; Shi, Yue; Jiang, Youxu; He, Jin-Sheng

    2015-01-01

    Plant biodiversity is often correlated with ecosystem functioning in terrestrial ecosystems. However, we know little about the relative and combined effects of above- and belowground biodiversity on multiple ecosystem functions (for example, ecosystem multifunctionality, EMF) or how climate might mediate those relationships. Here we tease apart the effects of biotic and abiotic factors, both above- and belowground, on EMF on the Tibetan Plateau, China. We found that a suite of biotic and abiotic variables account for up to 86% of the variation in EMF, with the combined effects of above- and belowground biodiversity accounting for 45% of the variation in EMF. Our results have two important implications: first, including belowground biodiversity in models can improve the ability to explain and predict EMF. Second, regional-scale variation in climate, and perhaps climate change, can determine, or at least modify, the effects of biodiversity on EMF in natural ecosystems. PMID:26328906

  3. Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale

    OpenAIRE

    de la Peña, Eduardo; Bonte, Dries

    2014-01-01

    Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The ...

  4. The variable effects of soil nitrogen availability and insect herbivory on aboveground and belowground plant biomass in an old-field ecosystem

    DEFF Research Database (Denmark)

    Blue, Jarrod D.; Souza, Lara; Classen, Aimée T.

    2011-01-01

    Nutrient availability and herbivory can regulate primary production in ecosystems, but little is known about how, or whether, they may interact with one another. Here, we investigate how nitrogen availability and insect herbivory interact to alter aboveground and belowground plant community biomass...... in an old-field ecosystem. In 2004, we established 36 experimental plots in which we manipulated soil nitrogen (N) availability and insect abundance in a completely randomized plot design. In 2009, after 6 years of treatments, we measured aboveground biomass and assessed root production at peak growth...... not be limiting primary production in this ecosystem. Insects reduced the aboveground biomass of subdominant plant species and decreased coarse root production. We found no statistical interactions between N availability and insect herbivory for any response variable. Overall, the results of 6 years of nutrient...

  5. Host range, symbiotic effectiveness and nodulation competitiveness ...

    African Journals Online (AJOL)

    ERIC-PCR DNA fingerprinting patterns were used to identify the isolates occupying nodules. All the isolates nodulated cowpea, groundnut (Arachis hypogeae) and mungbean (Vigna radiata), but only AII-2-1, AII-3-4 and BIII-2-2 nodulated soybean (Glycine max). Apart from cowpea where all the isolates were effective, there ...

  6. Screening for symbiotically effective and ecologically competitive ...

    African Journals Online (AJOL)

    This study was initiated to isolate and characterize chickpea rhizobia for their symbiotic effectiveness adapted to local environmental conditions. A total of seventy root nodule bacteria were isolated from different sampling sites in central and northern Ethiopia of which only 52% were rhizobia and the remaining were ...

  7. Effects of intrapopulation competition on morphological and ...

    African Journals Online (AJOL)

    The effects of population density on some agronomic traits of Corchorus olitorius were investigated by growing the seedlings in a field experiment at densities of 1, 2, 5, 10, 25, 50 and 100 plants per m2 during the raining season of 2006, at the Ojo campus of Lagos State University (LASU), Nigeria. The randomized block ...

  8. Interactions between above- and belowground organisms modified in climate change experiments

    Science.gov (United States)

    Stevnbak, Karen; Scherber, Christoph; Gladbach, David J.; Beier, Claus; Mikkelsen, Teis N.; Christensen, Søren

    2012-11-01

    Climate change has been shown to affect ecosystem process rates and community composition, with direct and indirect effects on belowground food webs. In particular, altered rates of herbivory under future climate can be expected to influence above-belowground interactions. Here, we use a multifactor, field-scale climate change experiment and independently manipulate atmospheric CO2 concentration, air and soil temperature and drought in all combinations since 2005. We show that changes in these factors modify the interaction between above- and belowground organisms. We use an insect herbivore to experimentally increase aboveground herbivory in grass phytometers exposed to all eight combinations of climate change factors for three years. Aboveground herbivory increased the abundance of belowground protozoans, microbial growth and microbial nitrogen availability. Increased CO2 modified these links through a reduction in herbivory and cascading effects through the soil food web. Interactions between CO2, drought and warming can affect belowground protozoan abundance. Our findings imply that climate change affects aboveground-belowground interactions through changes in nutrient availability.

  9. The Effect of Participation in Competitive Sports on School ...

    African Journals Online (AJOL)

    The purpose of the study was to determine the effects of participation in competitive sports on school connectedness among secondary school students. The demographics of gender, age, class, school type, school status and athletic status (participation/non participation in sport) were treated as independent variable while ...

  10. Effects of Cooperative and Competitive Learning Strategies on ...

    African Journals Online (AJOL)

    The effects of cooperative and competitive learning strategies on Students' performance in Mathematics were investigated in this study. Eighty (80) Senior Secondary II students made up of 40 males and 40 females were randomly selected from the population of a Secondary Commercial School in Uyo. These students ...

  11. Effects of Tariffication: Tariffs, Quotas and VERs under Monopolistic Competition

    OpenAIRE

    Jan G. Jorgensen; Philipp J. H. Schröder

    2002-01-01

    Recent rounds of GATT and later WTO have advocated widespread tariffication, meaning that existing non-tariff barriers be converted into import equivalent tariffs. From an economic point of view, the effects of such tariffication are not entirely clear. The paper presents a general equilibrium model with monopolistic competition to examine the welfare effects of tariffication. The ranking of pre- and post-tariffication welfare depends crucially on the nature of the initial trade barrier and t...

  12. Effects of confidence and anxiety on flow state in competition.

    Science.gov (United States)

    Koehn, Stefan

    2013-01-01

    Confidence and anxiety are important variables that underlie the experience of flow in sport. Specifically, research has indicated that confidence displays a positive relationship and anxiety a negative relationship with flow. The aim of this study was to assess potential direct and indirect effects of confidence and anxiety dimensions on flow state in tennis competition. A sample of 59 junior tennis players completed measures of Competitive State Anxiety Inventory-2d and Flow State Scale-2. Following predictive analysis, results showed significant positive correlations between confidence (intensity and direction) and anxiety symptoms (only directional perceptions) with flow state. Standard multiple regression analysis indicated confidence as the only significant predictor of flow. The results confirmed a protective function of confidence against debilitating anxiety interpretations, but there were no significant interaction effects between confidence and anxiety on flow state.

  13. The effect of swimming on oral health status: competitive versus non-competitive athletes

    Directory of Open Access Journals (Sweden)

    Simonetta D’ERCOLE

    2016-04-01

    Full Text Available ABSTRACT Young swimmers are particularly susceptible to the onset of oral diseases. Objective To evaluate the oral health status in young competitive and non-competitive swimmers, involving an assessment of salivary cariogenic bacteria and secretory IgA (S-IgA concentration. Material and Methods Before training sessions (T1, 54 competitive and 69 non-competitive swimmers had the following parameters assessed: decayed, missing, and filled teeth (DMFT, Plaque Index (PlI, and Gingival Index (GI. At T1 and after training sessions (T2, stimulated saliva was collected and microbiological and immunological analyses were performed. Results Competitive swimmers trained 2.02±0.09 hours 5 times a week, while non-competitive swimmers trained 2.03±0.18 hours a week. A total of 14.7% of competitive swimmers suffered dental trauma related to sports. Only 11.76% of the competitive swimmers took a daily dose of fluoride, against 32.65% of non-competitive swimmers (p=0.029. Neither group followed an established diet or presented statistically significant differences in terms of nutritional supplement drink and chocolate intake. There were statistically significant differences in terms of oral hygiene. No significant difference in clinical indexes (DMFT, PlI, and GI was present. S. mutans was harbored by 18.6% of competitive and the 32.2% of non-competitive swimmers. S. sobrinus was detected in 22.03% of competitive and 91.6% of non-competitive swimmers (p<0.05. S. sanguinis was found only in the saliva of competitive swimmers. The average S-IgA of competitive swimmers decreased significantly at T2 (p<0.05. The pool water had a daily average pH of 7.22. Conclusions Microbial markers, immune status and sporting characteristics are important for establishing guidelines for management of training load in order to minimize physical stress and the risk of oral infection.

  14. The impact of soil organism composition and activated carbon on grass-legume competition

    NARCIS (Netherlands)

    Wurst, S.; Van Beersum, S.

    2009-01-01

    Belowground mechanisms involved in plant competition are still poorly understood. Since plant species are differently affected by soil organisms, changes in soil community composition might affect interspecific competition with consequences for plant community structure. We studied whether soil

  15. Competition for a better future? Effects of competition on child care quality

    NARCIS (Netherlands)

    Akgündüz, Y.E.; Plantenga, J.

    2013-01-01

    Little is known about how competition affects child care centers’ quality. This paper examines the impact of competition on the quality of Dutch child care centers. The results show that high density of child care centers in an area improves scores in quality assessment measures. The positive

  16. The prerequisites for effective competition in restructured wholesale electricity markets

    International Nuclear Information System (INIS)

    Haas, R.; Auer, H.

    2006-01-01

    This paper argues that effective competition in reformed wholesale electricity markets can only be achieved if the following six prerequisites are met: (1) separation of the grid from generation and supply; (2) wholesale price deregulation; (3) sufficient transmission capacity for a competitive market and non-discriminating grid access; (4) excess generation capacity developed by a large number of competing generators; (5) an equilibrium relationship between short-term spot markets and the long-term financial instruments that marketers use to manage spot-market price volatility; (6) an essentially hands-off government policy that encompasses reduced oversight and privatization. The absence of any one of the first five conditions may result in an oligopoly or monopoly market whose economic performance does not meet the efficiency standards of a competently managed regulated electrical utility. (author)

  17. Intraspecific competition effects on Aethina tumida (Coleoptera: Nitidulidae).

    Science.gov (United States)

    Meikle, William G; Patt, Joseph M; Sammataro, Diana

    2012-02-01

    Two kinds of experiments were conducted with Aethina tumida Murray larvae over four temperatures: "consumption" experiments, in which larvae and diet were weighed to determine food consumption rates under conditions of unlimited food and few conspecifics; and "competition" experiments, in which varying numbers of larvae were presented with the same amount of honey and pollen diet, and larval weight at final instar was used to determine competition effects. In consumption experiments temperature, diet and their interaction all had significant effects on the ratio of larval weight to the weight of food consumed, which was higher at 24 degrees C than at any other temperature. In competition experiments, three relationships were examined and modeled: that between the number of larvae per experimental unit and the average weight of those larvae; that between average larval and adult weights; and that between average adult weight and survivorship to adult (emergence rate). An exponential decay function was fit to the relationship between number of larvae per experimental unit and their average weight. Average adult weight was linearly correlated with larval weight. Likewise, emergence rates for adults < 11.6 mg in weight were linearly correlated with adult weights, but no significant relationship was observed for heavier adults. Using these relationships, the reproductive potential for A. tumida were estimated for a frame of honey and pollen. Information on resource acquisition by A. tumida will be useful in evaluating the impact of different factors on beetle population dynamics, such as bee hygienic behavior or control strategies used by the beekeeper.

  18. Effects of Lexical Competition and Dialect Exposure on Phonological Priming.

    Science.gov (United States)

    Clopper, Cynthia G; Walker, Abby

    2017-03-01

    A cross-modal lexical decision task was used to explore the effects of lexical competition and dialect exposure on phonological form priming. Relative to unrelated auditory primes, matching real word primes facilitated lexical decision for visual real word targets, whereas competing minimal pair primes inhibited lexical decision. These effects were robust across two English vowel pairs (mid-front and low-front) and for two listener groups (mono-dialectal and multi-dialectal). However, both the most robust facilitation and the most robust inhibition were observed for the mid-front vowel words with few phonological competitors for the mono-dialectal listener group. The mid-front vowel targets were acoustically more distinct than the low-front vowel targets, suggesting that acoustic-phonetic similarity leads to stronger lexical competition and less robust facilitation and inhibition. The multi-dialectal listeners had more prior exposure to multiple different dialects than the mono-dialectal group, suggesting that long-term exposure to linguistic variability contributes to a more flexible processing strategy in which lexical competition extends over a longer period of time, leading to less robust facilitation and inhibition.

  19. Belowground Plant Dynamics Across an Arctic Landscape

    Science.gov (United States)

    Salmon, V. G.; Iversen, C. M.; Breen, A. L.; Thornton, P. E.; Wullschleger, S.

    2017-12-01

    High-latitude ecosystems are made up of a mosaic of different plant communities, all of which are exposed to warming at a rate double that observed in ecosystems at lower latitudes. Arctic regions are an important component of global Earth system models due to the large amounts of soil carbon (C) currently stored in permafrost as well their potential for increased plant C sequestration under warmer conditions. Losses of C from thawing and decomposing permafrost may be offset by increased plant productivity, but plant allocation to belowground structures and acquisition of limiting nutrients remain key sources of uncertainty in these ecosystems. The relationship between belowground plant traits and environmental conditions is not well understood, nor are tradeoffs between above- and belowground plant traits. To address these knowledge gaps, we sampled above- and belowground plant tissues along the Kougarok Hillslope on the Seward Peninsula, Alaska. The vegetation communities sampled included Alder shrubland, willow birch tundra, tussock tundra, dwarf shrub lichen tundra, and non-acidic mountain complex. Within each plant community, aboveground biomass was quantified and specific leaf area, leaf chemistry (%C, %N, %P and δ15N), and wood density were measured. Belowground fine-root biomass and rooting depth distribution were also determined at the community level. Fine roots from shrubs and graminoids were separated so that specific root area, diameter, and chemistry (%C, %N, %P and δ15N) could be assessed for these contrasting plant functional types. Initial findings indicate fine root biomass pools across the widely varying plant communities are constrained by soil depth, regardless of whether the rooting zone is restricted by permafrost or rock. The presence of Alnus viridis subspp. fruticosa, a deciduous shrub that facilitates nitrogen (N) fixation within its root nodules by Frankia bacteria, in Alder shrubland and willow birch tundra communities was associated

  20. Managing competitiveness in XXI century: effective business instruments

    OpenAIRE

    Styazhkin, M. S.; Стяжкин, М. С.

    2014-01-01

    The article is dedicated to the issues of managing competitiveness in the modern age of globalization, technology and innovation. The purpose of the paper is to analyze the influence of factors of competitiveness and offer effective tools for companies to create competitive advantages. Статья посвящена изучению вопросов управления конкурентоспособностью бизнеса в современный век глобализации, развития технологий и инноваций. Цель работы состоит в проведении анализа значимости факторов конк...

  1. The effects of electricity pricing on PHEV competitiveness

    Energy Technology Data Exchange (ETDEWEB)

    Huang Shisheng; Hodge, Bri-Mathias S. [School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, IN 47907 (United States); Taheripour, Farzad [Department of Agricultural Economics, Purdue University, 403W State Street, West Lafayette, IN 47907 (United States); Pekny, Joseph F.; Reklaitis, Gintaras V. [School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, IN 47907 (United States); Tyner, Wallace E., E-mail: wtyner@purdue.ed [Department of Agricultural Economics, Purdue University, 403W State Street, West Lafayette, IN 47907 (United States)

    2011-03-15

    Plug-in hybrid electric vehicles (PHEVs) will soon start to be introduced into the transportation sector, thereby raising a host of issues related to their use, adoption and effects on the electricity sector. Their introduction has the potential to significantly reduce carbon emissions from the transportation sector, which has led to government policies aimed at easing their introduction. If their widespread adoption is set as a target it is imperative to consider the effects of existing policies that may increase or decrease their adoption rate. In this study, we present a micro level electricity demand model that can gauge the effects of PHEVs on household electricity consumption and the subsequent economic attractiveness of the vehicles. We show that the electricity pricing policy available to the consumer is a very significant factor in the economic competitiveness of PHEVs. Further analysis shows that the increasing tier electricity pricing system used in California will substantially blunt adoption of PHEVs in the state; and time of use electricity pricing will render PHEVs more economically attractive in any state. - Research highlights: {yields} The effect of the California tiered electricity pricing is to render the PHEV uneconomic. {yields} The unintended consequence of tiered pricing is to make the PHEV unattractive to consumers. {yields} PHEVs will be more attractive in states with low electricity prices and flat rate pricing. {yields} Time of day pricing helps make PHEVs more attractive. {yields} PHEVs are not economically competitive either with a similar gasoline vehicle or Prius hybrid.

  2. Peer Effects, Social Networks, and Intergroup Competition in the Workplace

    DEFF Research Database (Denmark)

    Kato, Takao; Shu, Pian

    Using weekly data for defect rates (proportion of defective output) for all weavers in a Chinese textile firm during a 12 months (April 2003 - March 2004) period, we provide some of the first rigorous evidence on the presence and nature of peer effects in the manufacturing workplace. First...... novel evidence on the interplay between social networks (urban resident group and rural migrant group) and peer effects. Specifically, we find that a worker puts in more effort when she is working with more able outgroup teammates but not when working with more able ingroup teammates, pointing...... to intergroup competition as a powerful source of the peer effects. Such peer effects across the social network, combined with the presence of incentive to outperform teammates at this firm, are largely consistent with recent experimental evidence on the important role that group identities play in facilitating...

  3. Effect of Heterogeneity in Initial Geographic Distribution on Opinions’ Competitiveness

    Directory of Open Access Journals (Sweden)

    Alexander S. Balankin

    2015-05-01

    Full Text Available Spin dynamics on networks allows us to understand how a global consensus emerges out of individual opinions. Here, we are interested in the effect of heterogeneity in the initial geographic distribution of a competing opinion on the competitiveness of its own opinion. Accordingly, in this work, we studied the effect of spatial heterogeneity on the majority rule dynamics using a three-state spin model, in which one state is neutral. Monte Carlo simulations were performed on square lattices divided into square blocks (cells. Accordingly, one competing opinion was distributed uniformly among cells, whereas the spatial distribution of the rival opinion was varied from the uniform to heterogeneous, with the median-to-mean ratio in the range from 1 to 0. When the size of discussion group is odd, the uncommitted agents disappear completely after  3.30 ± 0.05 update cycles, and then the system evolves in a two-state regime with complementary spatial distributions of two competing opinions. Even so, the initial heterogeneity in the spatial distribution of one of the competing opinions causes a decrease of this opinion competitiveness. That is, the opinion with initially heterogeneous spatial distribution has less probability to win, than the opinion with the initially uniform spatial distribution, even when the initial concentrations of both opinions are equal. We found that although the time to consensus , the opinion’s recession rate is determined during the first 3.3 update cycles. On the other hand, we found that the initial heterogeneity of the opinion spatial distribution assists the formation of quasi-stable regions, in which this opinion is dominant. The results of Monte Carlo simulations are discussed with regard to the electoral competition of political parties.

  4. Above–belowground herbivore interactions in mixed plant communities are influenced by altered precipitation patterns

    Directory of Open Access Journals (Sweden)

    James Michael William Ryalls

    2016-03-01

    Full Text Available Root- and shoot-feeding herbivores have the capacity to influence one another by modifying the chemistry of the shared host plant. This can alter rates of nutrient mineralisation and uptake by neighbouring plants and influence plant–plant competition, particularly in mixtures combining grasses and legumes. Root herbivory-induced exudation of nitrogen (N from legume roots, for example, may increase N acquisition by co-occurring grasses, with knock-on effects on grassland community composition. Little is known about how climate change may affect these interactions, but an important and timely question is how will grass–legume mixtures respond in a future with an increasing reliance on legume N mineralisation in terrestrial ecosystems. Using a model grass–legume mixture, this study investigated how simultaneous attack on lucerne (Medicago sativa by belowground weevils (Sitona discoideus and aboveground aphids (Acyrthosiphon pisum affected a neighbouring grass (Phalaris aquatica when subjected to drought, ambient and elevated precipitation. Feeding on rhizobial nodules by weevil larvae enhanced soil water retention under ambient and elevated precipitation, but only when aphids were absent. While drought decreased nodulation and root N content in lucerne, grass root and shoot chemistry were unaffected by changes in precipitation. However, plant communities containing weevils but not aphids showed increased grass height and N concentrations, most likely associated with the transfer of N from weevil-attacked lucerne plants containing more nodules and higher root N concentrations compared with insect-free plants. Drought decreased aphid abundance by 54% but increased total and some specific amino acid concentrations (glycine, lysine, methionine, tyrosine, cysteine, histidine, arginine, aspartate and glutamate, suggesting that aphid declines were being driven by other facets of drought (e.g. reduced phloem hydraulics. The presence of weevil larvae

  5. 47 CFR 76.907 - Petition for a determination of effective competition.

    Science.gov (United States)

    2010-10-01

    ... competition. 76.907 Section 76.907 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST... for a determination of effective competition. (a) A cable operator (or other interested party) may file a petition for a determination of effective competition with the Commission pursuant to the...

  6. Where temperate meets tropical: Multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh community

    Science.gov (United States)

    McKee, K.L.; Rooth, J.E.

    2008-01-01

    Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2- and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

  7. Root interactions in a diverse grassland : the role of root traits in belowground productivity and decomposition

    NARCIS (Netherlands)

    Oram, Natalie J.

    2018-01-01

    Background Plant diversity influences ecosystem functioning. A positive relation between plant diversity and productivity above- and belowground has been established. Aboveground, this effect has been shown to be due to complementarity effects, interactions between species in a mixture

  8. The effect of knowledge based view on sustainable competitive advantage

    Directory of Open Access Journals (Sweden)

    Fatemeh Rezaee

    2015-11-01

    Full Text Available This study investigates the quantitative relationship between knowledge based view (i.e. empowering employees, promoting confidence, coding rules and sustainability competitive advantage (i.e. market, customer, financial within the banking industry of Iran. A valid research instrument was utilized to conduct a survey of 150 top- and middle-level managers from Mellat bank of Iran. With a response rate of 81.3 percent, 122 questionnaires are returned; the number of valid and usable questionnaires was 101. In order to determine validity of questionnaire, the content validity was used and Cronbach's alpha was used to determine the reliability of the questionnaire (KBV questionnaire 0.886, SCA questionnaire 0.843. Utilizing the structural equation modeling, and after a series of exploratory and confirmatory factor analyses, it was found that KBV had the greatest effect on the market centered SCA, while it had the least influence on the customer centered.

  9. The effect of manure management regulations on competitiveness

    DEFF Research Database (Denmark)

    Andersen, Mikael Skou

    2003-01-01

    Significant differences in the competitiveness of pig production along with growing international competition in the pigmeat market have raised concerns about the cost impact of environmental regulations on producers, particularly those regarding the management of manure. There appears to be a U...... regulations in different countries do not appear to be of a scale that could explain the general difference in pigmeat competitiveness between countries....

  10. Nitrogen soil emissions and belowground plant processes in Mediterranean annual pastures are altered by ozone exposure and N-inputs

    Science.gov (United States)

    Sánchez-Martín, L.; Bermejo-Bermejo, V.; García-Torres, L.; Alonso, R.; de la Cruz, A.; Calvete-Sogo, H.; Vallejo, A.

    2017-09-01

    Increasing tropospheric ozone (O3) and atmospheric nitrogen (N) deposition alter the structure and composition of pastures. These changes could affect N and C compounds in the soil that in turn can influence soil microbial activity and processes involved in the emission of N oxides, methane (CH4) and carbon dioxide (CO2), but these effects have been scarcely studied. Through an open top chamber (OTC) field experiment, the combined effects of both pollutants on soil gas emissions from an annual experimental Mediterranean community were assessed. Four O3 treatments and three different N input levels were considered. Fluxes of nitric (NO) and nitrous (N2O) oxide, CH4 and CO2 were analysed as well as soil mineral N and dissolved organic carbon. Belowground plant parameters like root biomass and root C and N content were also sampled. Ozone strongly increased soil N2O emissions, doubling the cumulative emission through the growing cycle in the highest O3 treatment, while N-inputs enhanced more slightly NO; CH4 and CO2 where not affected. Both N-gases had a clear seasonality, peaking at the start and at the end of the season when pasture physiological activity is minimal; thus, higher microorganism activity occurred when pasture had a low nutrient demand. The O3-induced peak of N2O under low N availability at the end of the growing season was counterbalanced by the high N inputs. These effects were related to the O3 x N significant interaction found for the root-N content in the grass and the enhanced senescence of the community. Results indicate the importance of the belowground processes, where competition between plants and microorganisms for the available soil N is a key factor, for understanding the ecosystem responses to O3 and N.

  11. Two-species asymmetric competition: effects of age structure on intra- and interspecific interactions.

    Science.gov (United States)

    Cameron, Tom C; Wearing, Helen J; Rohani, Pejman; Sait, Steven M

    2007-01-01

    1. The patterns of density-dependent resource competition and the mechanisms leading to competitive exclusion in an experimental two-species insect age-structured interaction were investigated. 2. The modes of competition (scramble or contest) and strength of competition (under- to overcompensatory) operating within and between the stages of the two species was found to be influenced by total competitor density, the age structure of the competitor community and whether competition is between stages of single or two species. 3. The effect of imposed resource limitation on survival was found to be asymmetric between stages and species. Environments supporting both dominant and subordinate competitors were found to increase survival of subordinate competitors at lower total competitor densities. Competitive environments during development within individual stage cohorts (i.e. small or large larvae), differed from the competitive environment in lumped age classes (i.e. development from egg-->pupae). 4. Competition within mixed-age, stage or species cohorts, when compared with uniform-aged or species cohorts, altered the position of a competitive environment on the scramble-contest spectrum. In some cases the competitive environment switched from undercompensatory contest to overcompensatory scramble competition. 5. Such switching modes of competition suggest that the relative importance of the mechanisms regulating single-species population dynamics (i.e. resource competition) may change when organisms are embedded within a wider community.

  12. The effects of individual and team competitions on performance, emotions, and effort.

    Science.gov (United States)

    Cooke, Andrew; Kavussanu, Maria; McIntyre, David; Ring, Christopher

    2013-04-01

    It is well documented that competition can affect performance and emotion in sport. However, our understanding of the comparative effects of individual and team competitions on performance and emotion is limited. We also know little about emotion-based mechanisms underlying the effects of different types of competition on performance. To address these issues, 64 participants completed a handgrip endurance task during time-trial, one-on-one, two-on-two, and four-on-four competitions while self-report and possible corroborative physiological measures of enjoyment, anxiety, and effort were assessed. Results indicated that performance, enjoyment, anxiety, and effort increased from individual to team competitions. The observed increases in performance were mediated by increased enjoyment and effort. Our findings illustrate differential effects of individual and team competitions on performance and emotion. Moreover, they indicate that both enjoyment-based and anxiety-based mechanisms can explain changes in performance among different types of individual and team competition.

  13. Root herbivory indirectly affects above- and below-ground community members and directly reduces plant performance

    NARCIS (Netherlands)

    Barber, N.A.; Milano, N.J.; Kiers, E.T.; Theis, N.; Bartolo, V.; Hazzard, R.V.; Adler, L.S.

    2015-01-01

    There is a widespread recognition that above- and below-ground organisms are linked through their interactions with host plants that span terrestrial subsystems. In addition to direct effects on plants, soil organisms such as root herbivores can indirectly alter interactions between plants and other

  14. Alteration of belowground carbon dynamics by nitrogen addition in southern California mixed conifer forests

    Science.gov (United States)

    N.S. Nowinski; S.E. Trumbore; G. Jimenez; M.E. Fenn

    2009-01-01

    Nitrogen deposition rates in southern California are the highest in North America and have had substantial effects on ecosystem functioning. We document changes in the belowground C cycle near ponderosa pine trees experiencing experimental nitrogen (N) addition (50 and 150 kg N ha−1 a−1 as slow release urea since 1997) at two end‐member...

  15. Incorporating climate into belowground carbon estimates in the national greenhouse gas inventory

    Science.gov (United States)

    Matthew B. Russell; Grant M. Domke; Christopher W. Woodall; Anthony W. D’Amato

    2015-01-01

    Refined estimation of carbon (C) stocks within forest ecosystems is a critical component of efforts to reduce greenhouse gas emissions and mitigate the effects of projected climate change through forest C management. Recent evidence has pointed to the importance of climate as a driver of belowground C stocks. This study describes an approach for adjusting allometric...

  16. Water-condition effects on rhizobia competition for cowpea nodule ...

    African Journals Online (AJOL)

    Both strains showed good competition with other indigenous rhizobia populations under favourable- and limited-water conditions. Competition between the inoculated strains in the mixture varied between water regimes. In non-limited-water conditions, strain ORS 3257 was the best competitor, whereas in limited-water ...

  17. Is Competition an Effective Classroom Tool for the Gifted Student?

    Science.gov (United States)

    Cropper, Carolyn

    1998-01-01

    Reviews the research on competition in classrooms for gifted students. It finds that competitive classroom structures involving extrinsic rewards may undermine the task commitment and involvement characteristic of intrinsic motivation and that this relationship is stronger for gifted students than for other students. Some short-term benefits of…

  18. Pitching effects of buoyancy during four competitive swimming strokes.

    Science.gov (United States)

    Cohen, Raymond C Z; Cleary, Paul W; Harrison, Simon M; Mason, Bruce R; Pease, David L

    2014-10-01

    The purpose of this study was to determine the pitching effects of buoyancy during all competitive swimming strokes--freestyle, backstroke, butterfly, and breaststroke. Laser body scans of national-level athletes and synchronized multiangle swimming footage were used in a novel markerless motion capture process to produce three-dimensional biomechanical models of the swimming athletes. The deforming surface meshes were then used to calculate swimmer center-of-mass (CoM) positions, center-of-buoyancy (CoB) positions, pitch buoyancy torques, and sagittal plane moments of inertia (MoI) throughout each stroke cycle. In all cases the mean buoyancy torque tended to raise the legs and lower the head; however, during part of the butterfly stroke the instantaneous buoyancy torque had the opposite effect. The swimming strokes that use opposing arm and leg strokes (freestyle and backstroke) had smaller variations in CoM positions, CoB positions, and buoyancy torques. Strokes with synchronized left-right arm and leg movement (butterfly and breaststroke) had larger variations in buoyancy torques, which impacts the swimmer's ability to maintain a horizontal body pitch for these strokes. The methodology outlined in this paper enables the rotational effects of buoyancy to be better understood by swimmers, allowing better control of streamlined horizontal body positioning during swimming to improve performance.

  19. Aboveground-belowground biodiversity linkages differ in early and late successional temperate forests.

    Science.gov (United States)

    Li, Hui; Wang, Xugao; Liang, Chao; Hao, Zhanqing; Zhou, Lisha; Ma, Sam; Li, Xiaobin; Yang, Shan; Yao, Fei; Jiang, Yong

    2015-07-17

    Understanding ecological linkages between above- and below-ground biota is critical for deepening our knowledge on the maintenance and stability of ecosystem processes. Nevertheless, direct comparisons of plant-microbe diversity at the community level remain scarce due to the knowledge gap between microbial ecology and plant ecology. We compared the α- and β- diversities of plant and soil bacterial communities in two temperate forests that represented early and late successional stages. We documented different patterns of aboveground-belowground diversity relationships in these forests. We observed no linkage between plant and bacterial α-diversity in the early successional forest, and even a negative correlation in the late successional forest, indicating that high bacterial α-diversity is not always linked to high plant α-diversity. Beta-diversity coupling was only found at the late successional stage, while in the early successional forest, the bacterial β-diversity was closely correlated with soil property distances. Additionally, we showed that the dominant competitive tree species in the late successional forest may play key roles in driving forest succession by shaping the soil bacterial community in the early successional stage. This study sheds new light on the potential aboveground-belowground linkage in natural ecosystems, which may help us understand the mechanisms that drive ecosystem succession.

  20. Root carbon flow from an invasive plant to belowground foodwebs

    Science.gov (United States)

    Mark A. Bradford; Michael S. Strickland; Jayna L. DeVore; John C. Maerz

    2012-01-01

    Aims Soil foodwebs are based on plant production. This production enters belowground foodwebs via numerous pathways, with root pathways likely dominating supply. Indeed, root exudation may fuel 30–50 % of belowground activity with photosynthate fixed only hours earlier. Yet we have limited knowledge of root fluxes of recent-photosynthate from invasive plants to...

  1. Linking aboveground and belowground interactions via induced plant defenses

    NARCIS (Netherlands)

    Bezemer, T.M.; Dam, van N.M.

    2005-01-01

    Plants have a variety of chemical defenses that often increase in concentration following attack by herbivores. Such induced plant responses can occur aboveground, in the leaves, and also belowground in the roots. We show here that belowground organisms can also induce defense responses aboveground

  2. Modelling the effect of size-asymmetric competition on size inequality

    DEFF Research Database (Denmark)

    Rasmussen, Camilla Ruø; Weiner, Jacob

    2017-01-01

    Abstract The concept of size asymmetry in resource competition among plants, in which larger individuals obtain a disproportionate share of contested resources, appears to be very straightforward, but the effects of size asymmetry on growth and size variation among individuals have proved...... to be controversial. It has often been assumed that competition among individual plants in a population has to be size-asymmetric to result in higher size inequality than in the absence of competition, but here we question this inference. Using very simple, individual-based models, we investigate how size symmetry...... of competition affects the development in size inequality between two competing plants and show that increased size inequality due to competition is not always strong evidence for size-asymmetric competition. Even absolute symmetric competition, in which all plants receive the same amount of resources...

  3. Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

    Science.gov (United States)

    Filgueiras, Camila Cramer; Willett, Denis S.; Junior, Alcides Moino; Pareja, Martin; Borai, Fahiem El; Dickson, Donald W.; Stelinski, Lukasz L.; Duncan, Larry W.

    2016-01-01

    Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes. PMID:27136916

  4. Biochemical Effects of Carbohydrate Supplementation in a Simulated Competition of Short Terrestrial Duathlon

    Directory of Open Access Journals (Sweden)

    Campbell Bill

    2006-12-01

    Full Text Available Abstract The purpose of the present study was to investigate the biochemical effects of carbohydrate supplementation in a simulated competition of short terrestrial duathlon. Ten duathletes participated in a simulated competition of short terrestrial duathlon 30 minutes after the ingestion of a 6% (30 g/500 ml maltodextrin solution (MALT or a placebo (PLA. This solution was also ingested every 15 minutes during the competition (12 g/200 ml; and immediately after the competition (18 g/300 ml. Samples of blood were collected at 3 time points: 1 at rest 1 hour before the beginning of the competition; 2 during the competition (approximately 1 hour and 45 minutes after the 1st collection; 3 immediately after the competition. Blood was analyzed for blood glucose, lactate, insulin and cortisol. Significant differences were observed in relation to blood glucose levels between MALT and PLA in the post-competition phase. There was also a significant difference in the lactate levels observed between MALT and PLA during the competition phase. Similarly, a significant difference in the cortisol concentrations during and after the competition phases (MALT and PLA were observed. We conclude that maltodextrin supplementation appears to be beneficial during short terrestrial duathlon competition as evidenced by biochemical markers.

  5. Effects of local lexical competition and regional dialect on vowel production.

    Science.gov (United States)

    Clopper, Cynthia G; Tamati, Terrin N

    2014-07-01

    Global measures of lexical competition, such as lexical neighborhood density, assume that all phonological contrasts contribute equally to competition. However, effects of local phonetic similarity have also been observed in speech production processes, suggesting that some contrasts may lead to greater competition than others. In the current study, the effect of local lexical competition on vowel production was examined across two dialects of American English that differ in the phonetic similarity of the low-front and low-back vowel pairs. Results revealed a significant interaction between regional dialect and local lexical competition on the acoustic distance within each vowel pair. Local lexical contrast led to greater acoustic distance between vowels, as expected, but this effect was significantly enhanced for acoustically similar dialect-specific variants. These results were independent of global neighborhood density, suggesting that local lexical competition may contribute to the realization of sociolinguistic variation and phonological change.

  6. A study on the effect of internet on competitiveness and customer loyalty in insurance industry based on Porter competitive forces

    Directory of Open Access Journals (Sweden)

    Samira Ghazavi

    2013-07-01

    Full Text Available This paper presents an empirical investigation to study the effect of internet in insurance industry in Iran. The proposed study designs a questionnaire, distributes it among some experts and analyzes them based on some statistical test. The survey is conducted within insurance firms located in one of provinces of Iran. The results of the study confirm that internet influences competition among providers, bargaining power of customers as well as suppliers, significantly. In addition, internet has meaningful impacts on starting a business, the threat of substitutes, customer satisfaction, perceived image as well as perceived quality. The results of this survey emphasizes on the relative importance of internet for building a better competitive insurance industry.

  7. Effects of competition on induction of crassulacean acid metabolism in a facultative CAM plant.

    Science.gov (United States)

    Yu, Kailiang; D'Odorico, Paolo; Li, Wei; He, Yongli

    2017-06-01

    Abiotic drivers of environmental stress have been found to induce CAM expression (nocturnal carboxylation) in facultative CAM species such as Mesembryanthemum crystallinum. The role played by biotic factors such as competition with non-CAM species in affecting CAM expression, however, remains largely understudied. This research investigated the effects of salt and water conditions on the competition between M. crystallinum and the C 3 grass Bromus mollis with which it is found to coexist in California's coastal grasslands. We also investigated the extent to which CAM expression in M. crystallinum was affected by the intensity of the competition with B. mollis. We found that M. crystallinum had a competitive advantage over B. mollis in drought and saline conditions, while B. mollis exerted strong competitive effects on M. crystallinum in access to light and soil nutrients in high water conditions. This strong competitive effect even outweighed the favorable effects of salt or water additions in increasing the biomass and productivity of M. crystallinum in mixture. Regardless of salt conditions, M. crystallinum did not switch to CAM photosynthesis in response to this strong competitive effect from B. mollis. Disturbance (i.e., grass cutting) reduced the competitive pressure by B. mollis and allowed for CAM expression in M. crystallinum when it was grown mixed with B. mollis. We suggest that moderate competition with other functional groups can enhance CAM expression in M. crystallinum, thereby affecting its plasticity and ability to cope with biological stress.

  8. Effects of Competition on Students' Self-Efficacy in Vicarious Learning

    Science.gov (United States)

    Chan, Joanne C. Y.; Lam, Shui-fong

    2008-01-01

    Background: Vicarious learning is one of the fundamental sources of self-efficacy that is frequently employed in educational settings. However, little research has investigated the effects of competition on students' writing self-efficacy when they engage in vicarious learning. Aim: This study compared the effects of competitive and…

  9. Multi-species coexistence in Lotka-Volterra competitive systems with crowding effects.

    Science.gov (United States)

    Gavina, Maica Krizna A; Tahara, Takeru; Tainaka, Kei-Ichi; Ito, Hiromu; Morita, Satoru; Ichinose, Genki; Okabe, Takuya; Togashi, Tatsuya; Nagatani, Takashi; Yoshimura, Jin

    2018-01-19

    Classical Lotka-Volterra (LV) competition equation has shown that coexistence of competitive species is only possible when intraspecific competition is stronger than interspecific competition, i.e., the species inhibit their own growth more than the growth of the other species. Note that density effect is assumed to be linear in a classical LV equation. In contrast, in wild populations we can observed that mortality rate often increases when population density is very high, known as crowding effects. Under this perspective, the aggregation models of competitive species have been developed, adding the additional reduction in growth rates at high population densities. This study shows that the coexistence of a few species is promoted. However, an unsolved question is the coexistence of many competitive species often observed in natural communities. Here, we build an LV competition equation with a nonlinear crowding effect. Our results show that under a weak crowding effect, stable coexistence of many species becomes plausible, unlike the previous aggregation model. An analysis indicates that increased mortality rate under high density works as elevated intraspecific competition leading to the coexistence. This may be another mechanism for the coexistence of many competitive species leading high species diversity in nature.

  10. Competitive Balance Measures in Sports Leagues: The Effects of Variation in Season Length

    OpenAIRE

    P Dorian Owen; Nicholas King

    2013-01-01

    Appropriate measurement of competitive balance is a cornerstone of the economic analysis of professional sports leagues. We examine the distributional properties of the ratio of standard deviations (RSD) of points percentages, the most widely used measure of competitive balance in the sports economics literature, in comparison with other standard-deviation-based measures. Simulation methods are used to evaluate the effects of changes in season length on the distributions of competitive balanc...

  11. Nitrogen fertilization decouples roots and microbes: Reductions in belowground carbon allocation limit microbial activity

    Science.gov (United States)

    Carrara, J.; Walter, C. A.; Govindarajulu, R.; Hawkins, J.; Brzostek, E. R.

    2017-12-01

    Nitrogen (N) deposition has enhanced the ability of trees to capture atmospheric carbon (C). The effect of elevated N on belowground C cycling, however, is variable and response mechanisms are largely unknown. Recent research has highlighted distinct differences between ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) trees in the strength of root-microbial interactions. In particular, ECM trees send more C to rhizosphere microbes to stimulate enzyme activity and nutrient mobilization than AM trees, which primarily rely on saprotrophic microbes to mobilize N. As such, we hypothesized that N fertilization would weaken root-microbial interactions and soil decomposition in ECM stands more than in AM stands. To test this hypothesis, we measured root-microbial interactions in ECM and AM plots in two long-term N fertilization studies, the Fernow Experimental Forest, WV and Bear Brook Watershed, ME. We found that N fertilization led to declines in plant C allocation belowground to fine root biomass, branching, and root exudation in ECM stands to a greater extent than in AM stands. As ECM roots are tightly coupled to the soil microbiome through energy and nutrient exchange, reductions in belowground C allocation were mirrored by shifts in microbial community composition and reductions in fungal gene expression. These shifts were accompanied by larger reductions in fungal-derived lignolytic and hydrolytic enzyme activity in ECM stands than in AM stands. In contrast, as the AM soil microbiome is less reliant on trees for C and are more adapted to high inorganic nutrient environments, the soil metagenome and transcriptome were more resilient to decreases in belowground C allocation. Collectively, our results indicate the N fertilization decoupled root-microbial interactions by reducing belowground carbon allocation in ECM stands. Thus, N fertilization may reduce soil turnover and increase soil C storage to a greater extent in forests dominated by ECM than AM trees.

  12. The roots of defense: plant resistance and tolerance to belowground herbivory.

    Directory of Open Access Journals (Sweden)

    Sean M Watts

    2011-04-01

    Full Text Available There is conclusive evidence that there are fitness costs of plant defense and that herbivores can drive selection for defense. However, most work has focused on above-ground interactions, even though belowground herbivory may have greater impacts on individual plants than above-ground herbivory. Given the role of belowground plant structures in resource acquisition and storage, research on belowground herbivores has much to contribute to theories on the evolution of plant defense. Pocket gophers (Geomyidae provide an excellent opportunity to study root herbivory. These subterranean rodents spend their entire lives belowground and specialize on consuming belowground plant parts.We compared the root defenses of native forbs from mainland populations (with a history of gopher herbivory to island populations (free from gophers for up to 500,000 years. Defense includes both resistance against herbivores and tolerance of herbivore damage. We used three approaches to compare these traits in island and mainland populations of two native California forbs: 1 Eschscholzia californica populations were assayed to compare alkaloid deterrents, 2 captive gophers were used to test the palatability of E. californica roots and 3 simulated root herbivory assessed tolerance to root damage in Deinandra fasciculata and E. californica. Mainland forms of E. californica contained 2.5 times greater concentration of alkaloids and were less palatable to gophers than island forms. Mainland forms of D. fasciculata and, to a lesser extent, E. californica were also more tolerant of root damage than island conspecifics. Interestingly, undamaged island individuals of D. fasciculata produced significantly more fruit than either damaged or undamaged mainland individuals.These results suggest that mainland plants are effective at deterring and tolerating pocket gopher herbivory. Results also suggest that both forms of defense are costly to fitness and thus reduced in the absence of

  13. Competitive foods sales are associated with a negative effect on school finances.

    Science.gov (United States)

    Peterson, Cora

    2011-06-01

    It is widely presumed that competitive foods-foods offered for sale in schools in addition to reimbursable federal meals programs-provide revenue that is essential to maintain school foodservices. However, evidence is lacking to demonstrate whether competitive foods sales truly improve foodservice financial viability. The aim of this research was to assess whether or not competitive foods sales have an overall positive financial effect on school foodservice finances. DESIGN AND STATISTICAL ANALYSES: This observational study used a multivariate time series analysis of annual foodservice financial data from repeated observations of 344 Minnesota public school districts between 2001 and 2008 (N=2,695). First, revenue from competitive foods was assessed in terms of whether or not such revenue displaced or complemented revenue from reimbursable meals. Second, profit from competitive foods was assessed in terms of whether or not such profit displaced or increased total school foodservice profit. Fixed effects models indicated small but significant negative relationships between competitive foods sales and reimbursable meals revenue, as well as overall foodservice profit. A 10% increase in competitive foods revenue was associated with a 0.1% decrease in reimbursable meals revenue (Psales (P<0.10). Study findings suggest that competitive foods can have a negative effect on school foodservice finances. Better understanding of foodservice finances could influence current approaches to improve school nutrition. Improved recordkeeping may be necessary to ensure that public funds are not used to subsidize schools' competitive offerings. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  14. Study on Pt-structured anodic alumina catalysts for catalytic combustion of toluene: Effects of competitive adsorbents and competitive impregnation methods

    Science.gov (United States)

    Zhang, Qi; Luan, Hongjuan; Li, Tao; Wu, Yongqiang; Ni, Yanhui

    2016-01-01

    Novel competitive impregnation methods were used to prepare high dispersion Pt-structured anodic alumina catalysts. It is found that competitive adsorbents owning different acidity result in different Pt loading amount and also exert great effects on Pt distribution, particle size and redox ability. The suitable adsorption ability of lactic acid led to its best activity for catalytic combustion of toluene. Co-competitive and pre-competitive impregnation methods were also compared and the mechanisms of two competitive methods were proposed. Co-competitive impregnation made Pt distribute more uniformly through pore channels and resulted in better catalytic activity, because of the weaker spatial constraint effect of lactic acid. Furthermore, the optimized Pt-structured anodic alumina catalyst also showed a good chlorine-resistance under moisture atmosphere, because water could promote the reaction of dichloromethane (DCM) transformation and clean chloride by-products to release more active sites.

  15. Competition effects of mergers. An event study of the German electricity market

    International Nuclear Information System (INIS)

    Keller, Andreas

    2010-01-01

    This paper investigates the competition effects of the entry of Vattenfall into the German electricity market. While the competition authorities supported the entry by approving Vattenfall's acquisition of three regional utilities, other market participants raised concerns over the emergence of an upcoming oligopoly in the German market for power generation. We contrast the efficiency hypothesis postulating pro-competitive effects of mergers with the market power hypothesis postulating anti-competitive effects. For the analysis of the two opposing hypotheses, we use an event study approach to the stock prices of Vattenfall's competitors in the German market. While we find no empirical evidence for increased market power in the German electricity market due to Vattenfall's mergers, there is some indication for efficiency increases. We therefore cannot oppose the view of the competition authorities predicting an overall positive effect for consumers as a result of Vattenfall's entry into the German electricity market. (author)

  16. The power of competition: Effects of social motivation on attention, sustained physical effort, and learning

    Directory of Open Access Journals (Sweden)

    Brynne Catherine DiMenichi

    2015-09-01

    Full Text Available Competition has often been implicated as a means to improve effort-based learning and attention. Two experiments examined the effects of competition on effort and memory. In Experiment 1, participants completed a physical effort task in which they were rewarded for winning an overall percentage, or for winning a competition they believed was against another player. In Experiment 2, participants completed a memory task in which they were rewarded for remembering an overall percentage of shapes, or more shapes than a competitor. We found that, in the physical effort task, participants demonstrated faster reaction times—a previous indicator of increased attention— in the competitive environment. Moreover, individual differences predicted the salience of competition’s effect. Furthermore, male participants showed faster reaction times and greater sustained effort as a result of a competitive environment, suggesting that males may be more affected by competition in physical effort tasks. However, in Experiment 2, participants remembered fewer shapes when competing, and later recalled less of these shapes during a post-test, suggesting that competition was harmful in our memory task. The different results from these two experiments suggest that competition can improve attention in a physical effort task, yet caution the use of competition in memory tasks.

  17. Effects of resource competition and herbivory on plant performance along a natural productivity gradient

    NARCIS (Netherlands)

    Van Der Wal, R; Egas, M; Bakker, J; van der Veen, A.

    1 The effects of resource competition and herbivory on a target species, Triglochin maritima, were studied along a productivity gradient of vegetation biomass in a temperate salt marsh. 2 Transplants were used to measure the impact of grazing, competition and soil fertility over two growing seasons.

  18. Investigation on the Effects of 12 Days Intensive Competition on Some Blood Parameters of Basketball Players

    Science.gov (United States)

    Gencer, Yildirim Gokhan; Coskun, Funda; Sarikaya, Mucahit; Kaplan, Seyhmus

    2018-01-01

    The aim of this study is to investigate the effect of intensive basketball competitions (10 official basketball games in 12 days intensive competition period) on blood parameters of basketball players. Blood samples were taken from the basketball players of the university team. The players were training regularly and they had no regular health…

  19. Study on effects of environmental regulation on competitiveness

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Man Ok; Lim, Hyun Jeong [Korea Environment Institute, Seoul (Korea)

    1999-12-01

    For Korea, the claim that the enhancement of environmental regulation is worsening the international competitiveness of the business is dominant. However, it is too early to reestablish a relationship between environmental regulation and competitiveness with the above new aspect. In fact, the economic development, which is brought a quantitative growth, and the maintenance of environmental quality, which is brought a qualitative growth, are very important on decision making in economic and social policy. In this study, it represents the results of existing positive studies on the relationship between the enhancement of environmental regulation, trade and productivity. Moreover, the objective of this study is on applying it based on the data of Korea. 86 refs., 13 figs., 35 tabs.

  20. Marsh Soil Responses to Nutrients: Belowground Structural and Organic Properties.

    Science.gov (United States)

    Coastal marsh responses to nutrient enrichment apparently depend upon soil matrix and whether the system is primarily biogenic or minerogenic. Deteriorating organic rich marshes (Jamaica Bay, NY) receiving wastewater effluent had lower belowground biomass, organic matter, and soi...

  1. Facilitative-competitive interactions in an old-growth forest: the importance of large-diameter trees as benefactors and stimulators for forest community assembly.

    Directory of Open Access Journals (Sweden)

    Andreas Fichtner

    Full Text Available The role of competition in tree communities is increasingly well understood, while little is known about the patterns and mechanisms of the interplay between above- and belowground competition in tree communities. This knowledge, however, is crucial for a better understanding of community dynamics and developing adaptive near-natural management strategies. We assessed neighbourhood interactions in an unmanaged old-growth European beech (Fagus sylvatica forest by quantifying variation in the intensity of above- (shading and belowground competition (crowding among dominant and co-dominant canopy beech trees during tree maturation. Shading had on average a much larger impact on radial growth than crowding and the sensitivity to changes in competitive conditions was lowest for crowding effects. We found that each mode of competition reduced the effect of the other. Increasing crowding reduced the negative effect of shading, and at high levels of shading, crowding actually had a facilitative effect and increased growth. Our study demonstrates that complementarity in above- and belowground processes enable F. sylvatica to alter resource acquisition strategies, thus optimising tree radial growth. As a result, competition seemed to become less important in stands with a high growing stock and tree communities with a long continuity of anthropogenic undisturbed population dynamics. We suggest that growth rates do not exclusively depend on the density of potential competitors at the intraspecific level, but on the conspecific aggregation of large-diameter trees and their functional role for regulating biotic filtering processes. This finding highlights the potential importance of the rarely examined relationship between the spatial aggregation pattern of large-diameter trees and the outcome of neighbourhood interactions, which may be central to community dynamics and the related forest ecosystem services.

  2. The impacts of climate change and belowground herbivory on aphids via primary metabolites

    Science.gov (United States)

    Ryalls, James M. W.

    CO2 and simulated root damage on aphids could be explained by changes in plant amino acid concentrations. Chapter five built on the mechanistic findings from chapter four to determine whether specific groups of amino acids were responsible for driving the effects of eT and eCO2 on aphid fecundity, longevity and intrinsic rate of increase (rm). Chapter six extended this research to the field to determine the plant-mediated effects of water stress and root herbivory on aphids in a mixed grass-legume system. Lucerne demonstrated an over compensatory growth response to root herbivory by S. discoideus larvae by increasing net root biomass and nodulation by 31% and 45%, respectively. eT negated the positive effects of eCO2 on weevil larval development, as well as on a number of lucerne characteristics (e.g. nodulation and amino acid concentrations) and aphid performance parameters (e.g. population growth, fecundity and rm). Root herbivory by S. discoideus negatively impacted aphids in general, although effects were dependent on feeding duration and herbivore arrival sequence (i.e. whether aphids fed on the plant before or after root herbivory). While drought negatively impacted aphid abundance, potentially via reduced phloem turgor and sap viscosity, the effects of eT, eCO2 and root herbivory on aphids were often driven by concentrations of specific amino acid groups. Nitrogen (N) leached from lacerated lucerne root nodules by S. discoideus led to increased concentrations of N in a neighbouring grass, Phalaris aquatica (Poaceae), with knock-on effects on plant competition and community dynamics. The opposing effects of eT and eCO2 on plant characteristics and both aboveground and belowground herbivores demonstrates the importance of combining trophic complexity with multiple climatic factors as a means of gaining realistic insights into how insect and plant communities will respond under future conditions. Identifying the specific amino acid changes underpinning aphid

  3. THE IMPACT OF MACROECONOMIC FACTORS ON COMPETITION POLICY EFFECTIVENESS WITHIN EUROPEAN UNION

    Directory of Open Access Journals (Sweden)

    Dragoi Ionut

    2012-12-01

    Full Text Available In the last decades, more and more countries have enacted competition laws, understanding the importance of this process in providing a normal functioning of the economy. Analyzing competition policy effectiveness is important not only because of the recent extent of the phenomenon, but also because of the impact of competition policy effectiveness on economic development and, in the current economic climate, on the economic recovery process. For this reason, quantitative evaluation for competition policy effectiveness became very useful as data handling and understanding the whole phenomenon are easier this way and an international perspective is provided. This was made possible by various international institutions that have created a system of aggregated indicators for the evaluation of competition law enforcement and competition advocacy (perceived effectiveness. The purpose of our research is to identify the macroeconomic factors that influence the effectiveness of competition law implementation within the European Union Member States. We have tasted the influence of 13 macroeconomic, using panel data methodology and data from the last four years. We obtained ß coefficients statistically significant only for 11 of them. The results are consistent with prior analyzed studies and economic logic: positive influence from market division, intensity of local competition, ethical behavior of firms, strength of auditing and reporting standards, efficiency of legal framework in settling disputes, protection of minority shareholders’ interests, public trust of politicians, economic dimension and market size and negative influence from corruption level and diversion of public funds. Based on the achieved results we can perform an analysis of principal components leading to causal space reduction with minimal information loss and without informational redundancy, creating the premises for building a model that explains competition policy

  4. Effects of intra- and interspecific competition on the sensitivity of aquatic macroinvertebrates to carbendazim.

    Science.gov (United States)

    Del Arco, Ana Isabel; Parra, Gema; Rico, Andreu; Van den Brink, Paul J

    2015-10-01

    The Ecological Risk Assessment of pesticides and other potentially toxic chemicals is generally based on toxicity data obtained from single-species laboratory experiments. In the field, however, contaminant effects are ubiquitously co-occurring with ecological interactions such as species competition and predation, which might influence the sensitivity of the individuals exposed to toxicants. The present experimental study investigated how intra- and interspecific competition influence the response of sensitive aquatic organisms to a pesticide. For this, the effects of the fungicide carbendazim were assessed on the mortality and growth of the snail Bithynia tentaculata and the crustacean Gammarus pulex under different levels of intraspecific and interspecific competition for a food resource. Interspecific competition was created by adding individuals of Radix peregra and Asellus aquaticus, respectively. The interaction of competition and carbendazim exposure significantly influenced B. tentaculata growth, however, combined effects on survival and immobility were considered transient and were less easily demonstrated. Positive influence of competition on G. pulex survival was observed under low-medium carbendazim concentrations and under medium-high density pressures, being partly related to cannibalistic and predation compensatory mechanisms, enhanced under food limiting conditions. This study shows that intra- and interspecific competition pressure may influence the response of sensitive aquatic organisms in a more complex way (positive, non-significant and negative effects were observed) than just increasing the sensitivity of the studied species, as has generally been hypothesized. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Does interspecific competition have a moderating effect on Taenia solium transmission dynamics in Southeast Asia?

    Science.gov (United States)

    Conlan, James V; Vongxay, Khamphouth; Fenwick, Stanley; Blacksell, Stuart D; Thompson, R C Andrew

    2009-09-01

    It is well understood that sociocultural practices strongly influence Taenia solium transmission; however, the extent to which interspecific parasite competition moderates Taenia transmission has yet to be determined. This is certainly the case in Southeast Asia where T. solium faces competition in both the definitive host (people) and the intermediate host (pigs). In people, adult worms of T. solium, T. saginata and T. asiatica compete through density-dependent crowding mechanisms. In pigs, metacestodes of T. solium, T. hydatigena and T. asiatica compete through density-dependent immune-mediated interactions. Here, we describe the biological and epidemiological implications of Taenia competition and propose that interspecific competition has a moderating effect on the transmission dynamics of T. solium in the region. Furthermore, we argue that this competitive ecological scenario should be considered in future research and surveillance activities examining T. solium cysticercosis and taeniasis in Southeast Asia.

  6. Effect of mode–mode competition on atom–atom entanglement

    International Nuclear Information System (INIS)

    Qin, Wu; Mao-Fa, Fang; Jian-Wu, Cai

    2010-01-01

    A system consisting of two atoms interacting with a two-mode vacuum is considered, where each atom is resonant with the two cavity modes through two different competing transitions. The effect of mode–mode competition on the atom–atom entanglement is investigated. We find that the entanglement between the two atoms can be induced by the mode–mode competition. For the initial atomic state |Ψ(0)}, whether the atoms are initially separated or entangled, a large or even maximal entanglement between them can be obtained periodically by introducing the mode–mode competition. For the initial atomic state |Φ(0)}, the strong mode–mode competition can prevent the two atoms entangled initially from suffering entanglement sudden death; besides, it makes them in a more stable and longer-lived entanglement than in the non-competition case. (classical areas of phenomenology)

  7. Competitive strategy in turbulent healthcare markets: an analysis of financially effective teaching hospitals.

    Science.gov (United States)

    Langabeer, J

    1998-01-01

    As the healthcare marketplace, characterized by declining revenues and heavy price competition, continues to evolve toward managed care, teaching hospitals are being forced to act more like traditional industrial organizations. Profit-oriented behavior, including emphases on market strategies and competitive advantage, is now a necessity if these hospitals are going to survive the transition to managed care. To help teaching hospitals evaluate strategic options that maximize financial effectiveness, this study examined the financial and operating data for 100 major U.S. teaching hospitals to determine relationships among competitive strategy, market environment, and financial return on invested capital. Results should help major hospitals formulate more effective strategies to combat environmental turbulence.

  8. Temperature Effect on Exploitation and Interference Competition among Microcystis aeruginosa, Planktothrix agardhii and, Cyclotella meneghiniana

    Directory of Open Access Journals (Sweden)

    Andreia Maria da Anunciação Gomes

    2015-01-01

    Full Text Available We studied the effect of temperature (18 and 30°C on growth and on the exploitation and interference competition of three species: Microcystis aeruginosa (MIJAC, Planktothrix agardhii (PAT, and Cyclotella meneghiniana (CCAP. Coculturing the organisms in batch systems allowed for the examination of both competitive interactions, while the interference competition was studied in cross-cultures. The experiments were done during 10–12 days, and samples were taken for chlorophyll-a analysis, using PHYTO-PAM. The temperature did not influence exploitation competition between MIJAC and other competitors and it was the best competitor in both temperatures. PAT presented higher growth rates than CCAP in competition at 18 and 30°C. The temperature influenced the interference competition. The growth of MIJAC was favored in strains exudates at 30°C, while CCAP was favored at 18°C, revealing that the optimum growth temperature was important to establish the competitive superiority. Therefore, we can propose two hypotheses: (i different temperatures may results in production of distinct compounds that influence the competition among phytoplankton species and (ii the target species may have different vulnerability to these compounds depending on the temperature. At last, we suggest that both the sensitivity and the physiological status of competing species can determine their lasting coexistence.

  9. Effect of cation competition on cadmium uptake from solution by the earthworm Eisenia fetida.

    NARCIS (Netherlands)

    Li, L.-Z.; Zhou, D.-M.; Wang, P.; Jin, S.-Y.; Peijnenburg, W.J.G.M.; Reinecke, A.J.; van Gestel, C.A.M.

    2009-01-01

    Metal speciation alone is insufficient to predict metal accumulation in aquatic and terrestrial organisms, because competition between cations can play an important role. In the present study, the effects of competing cations (Ca

  10. High intensity, short duration pulling in heavy horses: physiological effects of competition and rapid weight change.

    Science.gov (United States)

    Greco-Otto, Persephone; Massie, Shannon; Shields, Erin; Roy, Marie-France; Pajor, Edmond; Léguillette, Renaud

    2017-11-07

    The Heavy Horse Pull is a competition where teams of two horses pull an increasingly heavy sled for a short distance. Similar to human wrestlers, some horses may undergo rapid weight change in order to enter a lower weight category. The objectives were to study the physiological effects of this practice as well as of the pulling competition in draft horses. Fifty horses were divided into light-, middle- and heavyweight categories based on their arrival weights and competed 1-3 days after. Body weight was measured upon arrival and pre-competition. Blood was sampled for chemistry and high sensitivity cardiac troponin T (hscTnT) at arrival, pre- and post-competition in 34, 26 and 20 horses, respectively. Body weight increased significantly between arrival and pre-competition for light (7.2% (Median: 62.8Kg (41.7-77.0)) and middle (8.6% (Median: 80.5Kg (62.7-90.9)) weight categories. Change in body weight was correlated (r = 0.69, p = 0.002) with competition ranking for middleweights. The ratios of weight pulled to team body weight were 2.7 (1.9-2.8), 2.6 (2.5-2.6) and 2.4 (2.2-2.5) for the lightweights, middleweights and heavyweights, respectively. Blood chemistry indicated hemoconcentration on arrival in the middleweight and lightweight horses. Hemoconcentration was not seen on arrival in some horses with marked rapid weight change. Overall, no chemistry parameter changed between pre- and post-competition. The hscTnT stayed within normal range post-competition. While horses arrived to the event with indications of hemoconcentration, they appeared to have sufficient time to rehydrate prior to competition, and the effects of the competition were reversible within 3 h.

  11. The Principle of Effectiveness, Competition Law Remedies and the Limits of Adjudication

    OpenAIRE

    Lianos, I.

    2014-01-01

    The principle of effectiveness is closely related to the development of the emerging EU law on remedies. Its instrumental use has enabled the EU courts to restrict the principle of national procedural autonomy, when this was convenient in order to ensure the accomplishment of the aims set by EU competition law enforcement, and to establish EU-granted remedies, the most notable one being the right to claim competition law damages. The principle of effectiveness may also influence the design of...

  12. Effects of competition outcome on testosterone concentrations in humans: An updated meta-analysis.

    Science.gov (United States)

    Geniole, Shawn N; Bird, Brian M; Ruddick, Erika L; Carré, Justin M

    2017-06-01

    A contribution to a special issue on Hormones and Human Competition. Since Archer's (2006) influential meta-analysis, there has been a major increase in the number of studies investigating the effect of competition outcome on testosterone reactivity patterns in humans. Despite this increased research output, there remains debate as to whether competition outcome modulates testosterone concentrations. The present paper examines this question using a meta-analytic approach including papers published over the last 35years. Moreover, it provides the first meta-analytic estimate of the effect of competition outcome on testosterone concentrations in women. Results from a meta-analysis involving 60 effect sizes and >2500 participants indicated that winners of a competition demonstrated a larger increase in testosterone concentrations relative to losers (D=0.20)-an effect that was highly heterogeneous. This 'winner-loser' effect was most robust in studies conducted outside the lab (e.g., in sport venues) (D=0.43); for studies conducted in the lab, the effect of competition outcome on testosterone reactivity patterns was relatively weak (D=0.08), and only found in studies of men (D=0.15; in women: D=-0.04). Further, the 'winner-loser' effect was stronger among studies in which pre-competition testosterone was sampled earlier than (D=0.38, after trim and fill correction) rather than within (D=0.09) 10min of the start of the competition. Therefore, these results also provide important insight regarding study design and methodology, and will be a valuable resource for researchers conducting subsequent studies on the 'winner loser' effect. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Effect of habitat degradation on competition, carrying capacity, and species assemblage stability.

    Science.gov (United States)

    Calizza, Edoardo; Costantini, Maria Letizia; Careddu, Giulio; Rossi, Loreto

    2017-08-01

    Changes in species' trophic niches due to habitat degradation can affect intra- and interspecific competition, with implications for biodiversity persistence. Difficulties of measuring species' interactions in the field limit our comprehension of competition outcomes along disturbance gradients. Thus, information on how habitat degradation can destabilize food webs is scarce, hindering predictions regarding responses of multispecies systems to environmental changes. Seagrass ecosystems are undergoing degradation. We address effects of Posidonia oceanica coverage reduction on the trophic organization of a macroinvertebrate community in the Tyrrhenian Sea (Italy), hypothesizing increased trophic generalism, niche overlap among species and thus competition and decreased community stability due to degraded conditions. Census data, isotopic analysis, and Bayesian mixing models were used to quantify the trophic niches of three abundant invertebrate species, and intra- and interspecific isotopic and resource-use similarity across locations differing in seagrass coverage. This allowed the computation of (1) competition strength, with respect to each other and remaining less abundant species and (2) habitat carrying capacity. To explore effects of the spatial scale on the interactions, we considered both individual locations and the entire study area ("'meadow scale"). We observed that community stability and habitat carrying capacity decreased as P. oceanica coverage declined, whereas niche width, similarity of resource use and interspecific competition strength between species increased. Competition was stronger, and stability lower, at the meadow scale than at the location scale. Indirect effects of competition and the spatial compartmentalization of species interactions increased stability. Results emphasized the importance of trophic niche modifications for understanding effects of habitat loss on biodiversity persistence. Calculation of competition coefficients based

  14. Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale.

    Science.gov (United States)

    de la Peña, Eduardo; Bonte, Dries

    2014-08-01

    Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The strengths and directions of these responses have been scarcely addressed in the literature. Using Taraxacum officinale, the root-feeding nematode Meloidogyne hapla and the locust Schistocerca gregaria as a model species, we examined to what degree above- and belowground herbivory affect (1) plant growth responses, (2) the induction of plant defensive traits, that is, leaf trichomes, and (3) changes in dispersal-related seed traits and seed germination. We compared the performance of plants originating from different populations to address whether plant responses are conserved across putative different genotypes. Overall, aboveground herbivory resulted in increased plant biomass. Root herbivory had no effect on plant growth. Plants exposed to the two herbivores showed fewer leaf trichomes than plants challenged only by one herbivore and consequently experienced greater aboveground herbivory. In addition, herbivory had effects that reached beyond the individual plant by modifying seed morphology, producing seeds with longer pappus, and germination success.

  15. The Interdependence of Competition Policy, Consumer Policy and Regulation in Introducing and Safeguarding Effective Competition in the EU Telecommunications Market

    Directory of Open Access Journals (Sweden)

    Andreas Bartels

    2017-05-01

    Full Text Available Currently, the European Union finds itself in troubled waters. It has to prove that its benefits outweigh the costs of its endeavour. In this respect, an EU competition policy that focuses on consumer welfare is one way to gain support by the citizens of its member states. The Roaming Regulation that has reduced the mobile communications costs while travelling abroad serves as a good example for this approach. The EU Commission views consumer policy as another important factor to protect and benefit customers. In markets with natural monopolies, the two policies require the support of an effective regulatory policy. The research demonstrates that these three policies – if harmonised – are able to lead to an increase in consumer welfare (primarily by reducing prices and that they protect the rights and interests of consumers. In the case of telecommunications, several initiatives of the European Commission and of national regulatory authorities to falls in prices and forced operators to implement customer friendly rules and to protect customer data and privacy. The authors consider that the European Commission has tried to establish and harmonise rules across all member states in order to protect the interests and rights of consumers on the telecommunication market. The enforcement of competition and consumer policy within institutions from the telecom field certainly could promote the focus on consumers and the possibility to use a large “toolbox”. Harmonising and adjusting the policies across different countries and institutions and minimising any possible side effects is nevertheless a challenging task for the EU Commission in the future.

  16. THE EFFECT OF COMPETITIVE ADVANTAGE AND HUMAN ADVANTAGE ON INDUSTRIAL COMPETITIVE STRATEGY (Case Study: SMIs in Gorontalo Province

    Directory of Open Access Journals (Sweden)

    Trifandi Lasalewo

    2016-09-01

    Full Text Available Small and Medium Industries (SMIs have a strategic role in the Indonesian economy, as they earn 61.9 percent of the foreign exchange which goes to make up the nation’s Gross Domestic Product, and nationally they are able to absorb 97 percent of the workforce. The Global Competitiveness Report also notes that SMIs serve as the business units that affect every nation’s competitiveness. Considering this strategic role, the selection of a competitive strategy for these SMIs is absolutely necessary. Through an in-depth literature review, this study aims to explore what variables influence the competitive strategy of industries, particularly the SMIs. By using a Systematic Literature Review (SLR with a total of 31 main literature (articles, papers and books, this study has found two dominant factors that influence industrial competitive strategy: Competitive advantage and human advantage, which are subsequently developed into six independent variables (construct variables, i.e. cost, delivery, product quality, product variety, know-how and innovativeness, with a total of 44 indicators. The results of measurements of the sample of SMIs in Gorontalo Province, using Structural Equation Modeling, found that both competitive advantage and human advantage jointly influence 40.2 percent of the industrial competitive strategies. These results indicate that competitive strategies, such as creating products with unique features, on-time delivery, flexibility in production, and employee involvement in the innovations, are indispensable to SMIs in order for them to produce quality products and be able to maintain their advantage.

  17. Competitive outcome of Daphnia-Simocephalus experimental microcosms: salinity versus priority effects.

    Directory of Open Access Journals (Sweden)

    Cláudia Loureiro

    Full Text Available Competition is a major driving force in freshwaters, especially given the cyclic nature and dynamics of pelagic food webs. Competition is especially important in the initial species assortment during colonization and re-colonization events, which depends strongly on the environmental context. Subtle changes, such as saline intrusion, may disrupt competitive relationships and, thus, influence community composition. Bearing this in mind, our objective was to assess whether low salinity levels (using NaCl as a proxy alter the competitive outcome (measured as the rate of population biomass increase of Daphnia-Simocephalus experimental microcosms, taking into account interactions with priority effects (sequential species arrival order. With this approach, we aimed to experimentally demonstrate a putative mechanism of differential species sorting in brackish environments or in freshwaters facing secondary salinization. Experiments considered three salinity levels, regarding NaCl added (0.00, 0.75 and 1.50 g L(-1, crossed with three competition scenarios (no priority, priority of Daphnia over Simocephalus, and vice-versa. At lower NaCl concentrations (0.00 and 0.75 g L(-1, Daphnia was a significantly superior competitor, irrespective of the species inoculation order, suggesting negligible priority effects. However, the strong decrease in Daphnia population growth at 1.50 g L(-1 alleviated the competitive pressure on Simocephalus, causing an inversion of the competitive outcome in favour of Simocephalus. The intensity of this inversion depended on the competition scenario. This salinity-mediated disruption of the competitive outcome demonstrates that subtle environmental changes produce indirect effects in key ecological mechanisms, thus altering community composition, which may lead to serious implications in terms of ecosystem functioning (e.g. lake regime shifts due to reduced grazing and biodiversity.

  18. Maternal effects, but no good or compatible genes for sperm competitiveness in Australian crickets.

    Science.gov (United States)

    Dowling, Damian K; Nystrand, Magdalena; Simmons, Leigh W

    2010-05-01

    Explanations for the evolution of polyandry often center on the idea that females garner genetic benefits for their offspring by mating multiply. Furthermore, postcopulatory processes are thought to be fundamental to enabling polyandrous females to screen for genetic quality. Much attention has focused on the potential for polyandrous females to accrue such benefits via a sexy- or good-sperm mechanism, whereby additive variation exists among males in sperm competitiveness. Likewise, attention has focused on an alternative model, in which offspring quality (in this context, the sperm competitiveness of sons) hinges on an interaction between parental haplotypes (genetic compatibility). Sperm competitiveness that is contingent on parental compatibility will exhibit nonadditive genetic variation. We tested these models in the Australian cricket, Teleogryllus oceanicus, using a design that allowed us to partition additive, nonadditive genetic, and parental variance for sperm competitiveness. We found an absence of additive and nonadditive genetic variance in this species, challenging the direct relevance of either model to the evolution of sperm competitiveness in particular, and polyandry in general. Instead, we found maternal effects that were possibly sex-linked or cytoplasmically linked. We also found effects of focal male age on sperm competitiveness, with small increments in age conferring more competitive sperm.

  19. Does Competition Have an Effect on Price and Quality in Physiotherapy?

    Science.gov (United States)

    Pekola, Piia; Linnosmaa, Ismo; Mikkola, Hennamari

    2017-10-01

    We estimate the effect of competition on quality and prices in physiotherapy organised and financed by the Social Insurance Institution of Finland for disabled individuals. Within the physiotherapy market, firms participate in competitive bidding, prices are determined by the market, services are free at the point of use and firms are allowed to react to patient choice only by enhancing quality. Firm-level data (n = 854) regarding quality and price were analysed. Using 2SLS estimation techniques, we analysed the relationship between quality and competition, and price and competition. Our study found that competition has a negative (yet weak) effect on quality. Prices on the other hand are not affected by competition. The result is likely caused by imperfect information, because it seems that the Social Insurance Institution of Finland has provided too little information for patients to make adequate choices about proper service providers. We argue that by publishing quality information, it is possible to ease the decision-making of patients and influence the quality strategies of firms active in the physiotherapy market. Moreover, we found that competition appeared as an exogenous variable in this study. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  20. The effect of counter-trading on competition in electricity markets

    International Nuclear Information System (INIS)

    Dijk, Justin; Willems, Bert

    2011-01-01

    In a competitive electricity market, nodal pricing is the most efficient way to manage congestion. Counter-trading is inefficient as it gives the wrong long term signals for entry and exit of power plants. However, in a non-competitive market, additional entry will improve the competitiveness of the market, and will increase social benefit by reducing price-cost margins. This paper studies whether the potential pro-competitive entry effects could make counter-trading more efficient than nodal pricing. We find that this is unlikely to be the case, and expect counter-trading to have a negative effect on overall welfare. The potential benefits of additional competition (more competitive prices and lower production cost) do not outweigh the distortions (additional investment cost for the entrant, and socialization of the congestion cost to final consumers). - Research highlights: → 'Counter-trading' and 'nodal pricing' manage congestion in electric grids. → Nodal pricing gives superior locational prices. → Counter-trading induces extra investments in regions with a production surplus. → Extra investments improve competition, but are expected to be socially inefficient.

  1. The effect of counter-trading on competition in electricity markets

    Energy Technology Data Exchange (ETDEWEB)

    Dijk, Justin [IVM, VU University Amsterdam (Netherlands); Willems, Bert, E-mail: bwillems@tilburguniversity.ed [CentER and TILEC, Tilburg University, P.O. Box 90153 Room K308, NL-5000 LE Tilburg (Netherlands)

    2011-03-15

    In a competitive electricity market, nodal pricing is the most efficient way to manage congestion. Counter-trading is inefficient as it gives the wrong long term signals for entry and exit of power plants. However, in a non-competitive market, additional entry will improve the competitiveness of the market, and will increase social benefit by reducing price-cost margins. This paper studies whether the potential pro-competitive entry effects could make counter-trading more efficient than nodal pricing. We find that this is unlikely to be the case, and expect counter-trading to have a negative effect on overall welfare. The potential benefits of additional competition (more competitive prices and lower production cost) do not outweigh the distortions (additional investment cost for the entrant, and socialization of the congestion cost to final consumers). - Research highlights: {yields} 'Counter-trading' and 'nodal pricing' manage congestion in electric grids. {yields} Nodal pricing gives superior locational prices. {yields} Counter-trading induces extra investments in regions with a production surplus. {yields} Extra investments improve competition, but are expected to be socially inefficient.

  2. Effects of diffusion in competitive contact processes on bipartite lattices

    Science.gov (United States)

    de Oliveira, M. M.; Fiore, C. E.

    2017-05-01

    We investigate the influence of particle diffusion in the two-dimension contact process (CP) with a competitive dynamics in bipartite sublattices, proposed in de Oliveira and Dickman (2011 Phys. Rev. E 84 011125). The particle creation depends on its first and second neighbors and the extinction increases according to the local density. In contrast to the standard CP model, mean-field theory and numerical simulations predict three stable phases: inactive (absorbing), active symmetric and active asymmetric, signed by distinct sublattice particle occupations. Our results from MFT and Monte Carlo simulations reveal that low diffusion rates do not destroy sublattice ordering, ensuring the maintenance of the asymmetric phase. On the other hand, for diffusion larger than a threshold value D c , the sublattice ordering is suppressed and only the usual active (symmetric)-inactive transition is presented. We also show the critical behavior and universality classes are not affected by the diffusion.

  3. Outsourcing CIS to achieve a cost-effective competitive edge

    International Nuclear Information System (INIS)

    Haines, A.

    2000-01-01

    The ability to survive in a competitive electricity market is a function of the ability of a service provider to deliver superior levels of customer service and develop new and innovative products and services. More and more, the foundation of these new services and products is the customer information system which has the capability to provide vast amounts of usage data and billing information; access to this data enables service providers to introduce new and innovative services and implement targeted marketing initiatives. Recent trend by progressive electricity providers appears to be to outsource specific information technology functions such as customer information systems (CIS) as a way to minimize capital investment, take advantage of leading edge technologies and leverage the expertise of niche service providers. Advantages of outsourcing, and factors important in the selection of an outsourcing partner are discussed

  4. Effects of intraspecific larval competition on adult longevity in the mosquitoes Aedes aegypti and Aedes albopictus.

    Science.gov (United States)

    Reiskind, M H; Lounibos, L P

    2009-03-01

    Larval competition is common in container-breeding mosquitoes. The impact of competition on larval growth has been thoroughly examined and findings that larval competition can lead to density-dependent effects on adult body size have been documented. The effects of larval competition on adult longevity have been less well explored. The effects of intraspecific larval densities on the longevity of adults maintained under relatively harsh environmental conditions were tested in the laboratory by measuring the longevity of adult Aedes aegypti (L.) and Aedes albopictus (Skuse) (Diptera: Culicidae) that had been reared under a range of larval densities and subsequently maintained in high- or low-humidity regimes (85% or 35% relative humidity [RH], respectively) as adults. We found significant negative effects of competition on adult longevity in Ae. aegypti, but not in Ae. albopictus. Multivariate analysis of variance suggested that the negative effect of the larval environment on the longevity of Ae. aegypti adults was most strongly associated with increased development time and decreased wing length as adults. Understanding how larval competition affects adult longevity under a range of environmental conditions is important in establishing the relationship between models of mosquito population regulation and epidemiological models of vector-borne disease transmission.

  5. The effects of training and competition on achievement goals, motivational responses, and performance in a golf-putting task

    NARCIS (Netherlands)

    Pol, P.K.C. van de; Kavussanu, M.; Ring, C.

    2012-01-01

    This study examined whether (a) training and competition influence achievement goals, effort, enjoyment, tension, and performance; (b) achievement goals mediate the effects of training and competition on effort, enjoyment, tension, and performance; and (c) the context influences the relationships

  6. Increasing the competitiveness of banks

    OpenAIRE

    Badaeva V.; Makukhina Y.

    2017-01-01

    The article examines about the essence of competitiveness of banks, the ways of improving it, competitive advantages and factors which influence the effectiveness and competitiveness of banking institutions.

  7. The Effect of Coaches' Controlling Style on the Competitive Anxiety of Young Athletes.

    Science.gov (United States)

    Ramis, Yago; Torregrosa, Miquel; Viladrich, Carme; Cruz, Jaume

    2017-01-01

    Framed on a Self-Determination Theory perspective, the purpose of this study was to explore the predictive capacity of coaches' interpersonal controlling style on the competitive anxiety of young athletes, considering the mediating effect of the athletes' controlled motivation on this relationship. The sample consisted of 1166 athletes, aged between 9 and 18, who ranked their perceptions of coaches' controlling style, as well as the reasons for participating in sport and their competitive anxiety before or during competition. The structural models assessing both the direct effect of the controlling style on the anxiety and the complete mediated effect of the controlled motivation on this relationship revealed good fit indices. However, a significant difference of the chi-square was obtained when comparing these models to the partial mediation model, providing evidence of this last model to be more adequate to describe the relationship between coaches' controlling style and athletes' competitive anxiety. Positive significant effects of coach controlling style on the three forms of competitive anxiety were found (β CS - SA = 0.21, p anxiety in a direct way. Although this style also predicts athletes' motivation to participate, this indirect path seems to predict competitive anxiety in a less clear way. We discuss our results facing them up to Vallerand's hierarchical model postulates, focusing on the relevant influence of coaches on the young athletes' experience in the sport context.

  8. Individually-psychological discrepancies of the qualified athletes and their effect on productivity of competitive activity

    Directory of Open Access Journals (Sweden)

    Tolkunova I.V.

    2009-10-01

    Full Text Available Extreme effect of competitive conditions calls in sportsmen a condition nervously - a mental pressure. Sportsmen do not test these pressure (or pressure in much smaller degree during training exercises. Research is guided on study of individual psychological properties of the personality of sportsmen from 18 till 32 years (specialization track and field athletics leaps. The interrelation of sports outcomes of main competitions of a season with separate parameters of properties of the personality of sportsmen is exhibited.

  9. Money and politics: The effects of campaign spending limits on political competition and incumbency advantage

    OpenAIRE

    Avis, Eric; do Amaral, Claudio A. Ferraz; Finan, Frederico S.; Varjão, Carlos

    2017-01-01

    This paper examines the effects of campaign spending limits on political competition and incumbency advantage. We study a reform in Brazil that imposed limits on campaign spending for mayoral elections. These limits were implemented with a discontinuous kink which we exploit for causal identification. We find that stricter limits increase political competition by creating a larger pool of candidates that is on average less wealthy. Moreover, we find that stricter spending limits reduce the in...

  10. The Effects Of Competition Policy: Merger Approval, Entry Barrier Removal, Antitrust Enforcement Compared

    OpenAIRE

    Svetlana B. Avdasheva; Dina V. Tsytsulina

    2014-01-01

    There is little evidence on the comparative effectiveness of different competition policy measures, especially in transition economies. This research represents the effort to expand the financial event study method for the assessment of different competition policy measures: merger control, antitrust investigations on abuse of dominance, and changes of import tariffs in the Russian ferrous and non-ferrous metals markets from 2007 to 2012. According to the reaction of financial market, mergers...

  11. Power market competition

    International Nuclear Information System (INIS)

    Kelly, J.

    1998-01-01

    In the Unites States the prospect of greater competition in wholesale power market was immediately eclipsed by talk of retail competition. Attempts to move to retail competition have been costly and complex. Prudent public policy and economic analyses suggest that retail competition not be implemented until it can first be demonstrated that effective competition exists in wholesale power markets [it

  12. Unearthing belowground bud banks in fire-prone ecosystems.

    Science.gov (United States)

    Pausas, Juli G; Lamont, Byron B; Paula, Susana; Appezzato-da-Glória, Beatriz; Fidelis, Alessandra

    2018-03-01

    Despite long-time awareness of the importance of the location of buds in plant biology, research on belowground bud banks has been scant. Terms such as lignotuber, xylopodium and sobole, all referring to belowground bud-bearing structures, are used inconsistently in the literature. Because soil efficiently insulates meristems from the heat of fire, concealing buds below ground provides fitness benefits in fire-prone ecosystems. Thus, in these ecosystems, there is a remarkable diversity of bud-bearing structures. There are at least six locations where belowground buds are stored: roots, root crown, rhizomes, woody burls, fleshy swellings and belowground caudexes. These support many morphologically distinct organs. Given their history and function, these organs may be divided into three groups: those that originated in the early history of plants and that currently are widespread (bud-bearing roots and root crowns); those that also originated early and have spread mainly among ferns and monocots (nonwoody rhizomes and a wide range of fleshy underground swellings); and those that originated later in history and are strictly tied to fire-prone ecosystems (woody rhizomes, lignotubers and xylopodia). Recognizing the diversity of belowground bud banks is the starting point for understanding the many evolutionary pathways available for responding to severe recurrent disturbances. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  13. Interactions between above- and belowground biota : importance for small-scale vegetation mosaics in a grassland ecosystem

    NARCIS (Netherlands)

    Blomqvist, N.M.; Olff, H.; Blaauw, M.B.; Bongers, T.; Putten, van der W.H.

    2000-01-01

    Grasslands are often characterised by small-scale mosaics in plant community composition that contribute to their diversity. Although above- and belowground biota can both cause such mosaics, few studies have addressed their interacting effects. We studied multi-trophic interactions between

  14. Below-ground process responses to elevated CO2 and temperature: a discussion of observations, measurement methods, and models

    Science.gov (United States)

    Elise Pendall; Scott Bridgham; Paul J. Hanson; Bruce Hungate; David W. Kicklighter; Dale W. Johnson; Beverly E. Law; Yiqi Luo; J. Patrick Megonigal; Maria Olsrud; Michael G. Ryan; Shiqiang Wan

    2004-01-01

    Rising atmospheric CO2 and temperatures are probably altering ecosystem carbon cycling, causing both positive and negative feedbacks to climate. Below-ground processes play a key role in the global carbon (C) cycle because they regulate storage of large quantities of C, and are potentially very sensitive to direct and indirect effects of elevated...

  15. Effect of playing violent video games cooperatively or competitively on subsequent cooperative behavior.

    Science.gov (United States)

    Ewoldsen, David R; Eno, Cassie A; Okdie, Bradley M; Velez, John A; Guadagno, Rosanna E; DeCoster, Jamie

    2012-05-01

    Research on video games has yielded consistent findings that violent video games increase aggression and decrease prosocial behavior. However, these studies typically examined single-player games. Of interest is the effect of cooperative play in a violent video game on subsequent cooperative or competitive behavior. Participants played Halo II (a first-person shooter game) cooperatively or competitively and then completed a modified prisoner's dilemma task to assess competitive and cooperative behavior. Compared with the competitive play conditions, players in the cooperative condition engaged in more tit-for-tat behaviors-a pattern of behavior that typically precedes cooperative behavior. The social context of game play influenced subsequent behavior more than the content of the game that was played.

  16. The effects of greening the supplier and innovation on environmental performance and competitive advantage

    Directory of Open Access Journals (Sweden)

    Unine van den Berg

    2013-10-01

    Full Text Available Companies in South Africa should realise the important influence of greening their suppliers and of innovation to achieve environmental goals and competitive advantages. In order to prove this, a questionnaire survey was conducted with 75 companies from 11 industries in the City of Johannesburg Metropolitan Municipality region, South Africa. A confirmatory factor analysis was done, followed by bivariate correlations to determine the strength of association between the latent constructs. Correlations between greening the supplier, innovation, environmental performance and competitive advantages were done. The research found that a green innovative process had a significant effect on environmental performance. Green managerial innovation further had a significant correlation with competitive advantage. The primary result of the study indicated that all the constructs positively related to each other, meaning that greening suppliers, by means of green innovation, leads to an enhanced environmental performance and to competitive advantages.

  17. The effects of greening the supplier and innovation on environmental performance and competitive advantage

    Directory of Open Access Journals (Sweden)

    Unine van den Berg

    2013-05-01

    Full Text Available Companies in South Africa should realise the important influence of greening their suppliers and of innovation to achieve environmental goals and competitive advantages. In order to prove this, a questionnaire survey was conducted with 75 companies from 11 industries in the City of Johannesburg Metropolitan Municipality region, South Africa. A confirmatory factor analysis was done, followed by bivariate correlations to determine the strength of association between the latent constructs. Correlations between greening the supplier, innovation, environmental performance and competitive advantages were done. The research found that a green innovative process had a significant effect on environmental performance. Green managerial innovation further had a significant correlation with competitive advantage. The primary result of the study indicated that all the constructs positively related to each other, meaning that greening suppliers, by means of green innovation, leads to an enhanced environmental performance and to competitive advantages.

  18. Temporal priority effects on competition are not consistent among intermountain grassland species

    Science.gov (United States)

    Zuo, Shengpeng; Li, Hongli; Ma, Yongqing; Callaway, Ragan M.

    2016-08-01

    Previous work indicates that priority effects exist, but mechanisms are not well understood. So we explored shifts in competitive outcomes and intensities as a potential general mechanism. In a standard greenhouse experiment the temporal priority effects of the target species Pseudoroegneria spicata and its competitive responses to five receptor species, i.e., Bromus ciliatus, Bromus marginatus, Coreopsis tinctoria, Senecio atratus, and Solidago canadensis were evaluated. P. spicata adults with a high root: shoot ratio had a significant inhibitory priority effect on B. ciliatus, B. marginatus, and C. tinctoria. Compared with the target species, under later and simultaneous sowing, B. ciliatus, B. marginatus, C. tinctoria, and S. atratus exhibited an increasing trend in terms of competition. However, S. canadensis did not display priority effects. In addition, the gram per gram competitive effect of P. spicata depended on the receptor species in the following order: B. marginatus > B. ciliatus > C. tinctoria > S. atratus. There were positive relationships between the relative interaction indices and the root: shoot ratios in B. ciliatus, B. marginatus, and C. tinctoria, thereby suggesting that the early germination or emergence of P. spicata may reduce the root: shoot ratios of these receptors. The results of this study indicate that priority effects occurred in early colonizers with high root: shoot ratios and greater competitive capacities.

  19. Competitive effects of fire-resistant saplings on their fire-sensitive neighbors are greater than the reverse

    Science.gov (United States)

    J. Stephen Brewer

    2015-01-01

    Although repeated fires are generally thought to reduce competition, direct tests of this hypothesis are rare. Furthermore, recent theory predicts that fires can increase competitive effects of fireresistant species on fire-sensitive species and thus create stable assemblages dominated by the former. In this study, I quantified competition between saplings of fire-...

  20. Study on the impact of cultural factors on the industrial competitiveness of oolong tea based on spatial effects

    Directory of Open Access Journals (Sweden)

    Feng Qu

    2017-06-01

    Full Text Available According to industrial competitiveness evaluation of oolong tea, we would love to study different effects of cultural factors of industrial competitiveness, especially the spatial effects. Researches indicate that the cultural factors affected the competitiveness of tea industry sharply, which have spatial effects. The researches of spatial effects of cultural factors are useful in understanding their spillover effects, which is conducive to study the cultural influence of oolong tea industry.

  1. Competitive Advantages of Effective Relationships of Business Entities as a Basis for Economic Development of Ukraine

    Directory of Open Access Journals (Sweden)

    Butenko Nataliia V.

    2016-11-01

    Full Text Available The aim of the article is to determine the transformation of sense of relationships between business entities in the national economy as well as basic ideas and principles of forming competitive advantages of effective relationships. The objective preconditions for the transition from the confrontation strategy to relationships as a basis of interaction of business entities in the structure of the national economy are analyzed. It is determined that the weakening of the antagonistic dominant of competitive relations and the growing importance of a constructive component of partnership has become a background of the desire of business entities to establish effective relationships. The attention is focused on the trends of the cooperation and integration approach to competitive behavior, which is manifested in such forms of competitive interactions as coordination, constructive interaction and competitive collaboration in order to achieve individual and common goals of competitive relationships of the entities. The competitive advantages based on establishing long-term and effective relationships are considered. The peculiarities in the formation of the system of relationships in the insurance market are justified, in particular the causes hindering the development of relationships in the sphere of security are determined, the main partners — entities in the system of relationships in the insurance market are identified, the levels of relationships management in the insurance market are determined. Among the advantages of the use of effective relationships in the field of insurance are the following: improving the company’s image, attracting new customers, additional sales of insurance services, limiting the access of competitors’ offers, more efficient use of the advertising budget, improving the efficiency of the development of new insurance products and services, increasing the profits and value of brands, improving relations with

  2. Competition between the Thermal Gradient and the Bimorph Effect in Locally Heated MEMS Actuators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Mølhave, Kristian; Kristensen, Anders

    2009-01-01

    modeling. As a result, bidirectional bending has been experimentally observed and interpreted as the competition between bimorph and thermal gradient effects. The competition has illustrated the importance of including the thermal gradient effect in the behavior analysis of bimorph driven MEMS/NEMS devices.......We have investigated the influence of thermal gradient effects in inhomogeneously heated MEMS/NEMS. The actuation perturbations caused by thermal gradients have been studied through static optothermal actuation experiments of a bi-material polymer based cantilever and supported by finite element...

  3. Effects of intraspecific competition on the life cycle of the stonefly, Nemurella pictetii (Plecoptera: Nemouridae).

    Science.gov (United States)

    Lieske, Reimo; Zwick, Peter

    2008-04-16

    Considerable variation of life cycle duration in given insect species has been frequently recorded. Splitting of populations into cohorts with different life cycle lengths may occur, sometimes even between siblings from the same batch. Larval populations of the stonefly Nemurella pictetii in central Europe regularly split into a very fast developing and a normal univoltine cohort, leading to partial multivoltinism. The causes for such variation remain unknown but presumably act on the larval stage in which most of the life cycle is spent. We therefore studied possible effects of intraspecific competition on growth and development of larvae in the laboratory. Intraspecific competition had important influence on growth and development of the larvae. High larval densities led to reduced growth and retarded development through interference, not through exploitative competition. All specimens were negatively affected by frequent encounters and the resulting disturbance. There were no dominant individuals able to grow and develop faster than the rest, at the expense of the others. Differences in life cycle length of Nemurella pictetii may result from different larval densities in different microhabitats and resultant different degrees of interference competition. Although competition alone probably does not cause splitting of populations into cohorts with different life cycle duration differences in size and development caused by other factors are certainly enhanced by intraspecific competition.

  4. [Root growth characteristics and competitive effects of Ageratina adenophora and four functional type herbaceous plants].

    Science.gov (United States)

    Jiang, Zhi-Lin; Wang, Wu-Yun; Lei, Gui-Sheng; Gui, Fu-Rong; Liu, Wan-Xue; Li, Zheng-Yue

    2014-10-01

    A field experiment was conducted to explore the root competitive effects of Ageratina adenophora and Setaria sphacelata, S. yunnanensis, Eupatorium fortunei, Chenopodium serotinum in monoculture and mixture, and the relative competitive abilities were evaluated. The results showed that the root length, superficial area and volume of A. adenophora in mixture were lower than in monoculture, but those of S. sphacelata were higher in mixture than in monoculture. The biomass of A. adenophora in mixture decreased by 77.1% and that of S. sphacelata increased by 80.4% compared with those in monoculture. The relative yield and competitive balance index of S. sphacelata were significantly higher than those of A. adenophora, and the relative yield was about 1.0, suggesting that the underground competitive ability of S. sphacelata was higher than A. adenophora. The root morphology of S. yunnanensis in monoculture and mixture was higher than those of A. adenophora, but the root morphology of two species in mixture was lower than in monoculture. The biomass of A. adenophora and S. yunnanensis in mixture decreased by 45.3% and 22.8% compared with those in monoculture, respectively. Competition effect parameters showed that A. adenophora was a mutual antagonism with S. yunnanensis. The root morphology of E. fortunei and A. adenophora in mixture showed no significant difference compared with that in monoculture. The biomass of A. adenophora and E. fortunei was lower than that in monoculture, respectively. Competition effect parameters showed that A. adenophora was a superior competitor. In the mixture of A. adenophora and C. serotinum, the root morphology parameters and competitive ability of A. adenophora were superior to those of C. serotinum. Above all, S. sphacelata is a preference plant material to control the A. adenophorum invasion and recover biodiversity in A. adenophorum invasion fields.

  5. Effects of informal competition on innovation performance: the case of pacific alliance

    Directory of Open Access Journals (Sweden)

    Jorge Heredia

    2017-12-01

    Full Text Available This study evaluates the impact of informal competition on the innovation performance of formal firms in emerging economies. A theoretical model under the strategy tripod framework is proposed. It analyzes the effects of Institutional factors as the quality of governance and market labor rigidities on innovation performance, and the mediating effect of informal competition. It is used the Causal Mediation Analysis with data from 3,268 companies from the World Bank Enterprise Survey from countries of the Pacific Alliance (Chile, Colombia, Mexico, and Peru. The results state that informal competition has a negative effect on the innovation performance of formal companies. Based on these findings, It is suggested some promising avenues for future research and managerial implications.

  6. Impacts of mangrove density on surface sediment accretion, belowground biomass and biogeochemistry in Puttalam Lagoon, Sri Lanka

    Science.gov (United States)

    Phillips, D.H.; Kumara, M.P.; Jayatissa, L.P.; Krauss, Ken W.; Huxham, M.

    2017-01-01

    Understanding the effects of seedling density on sediment accretion, biogeochemistry and belowground biomass in mangrove systems can help explain ecological functioning and inform appropriate planting densities during restoration or climate change mitigation programs. The objectives of this study were to examine: 1) impacts of mangrove seedling density on surface sediment accretion, texture, belowground biomass and biogeochemistry, and 2) origins of the carbon (C) supplied to the mangroves in Palakuda, Puttalam Lagoon, Sri Lanka. Rhizophora mucronata propagules were planted at densities of 6.96, 3.26, 1.93 and 0.95 seedlings m−2along with an unplanted control (0 seedlings m−2). The highest seedling density generally had higher sediment accretion rates, finer sediments, higher belowground biomass, greatest number of fine roots and highest concentrations of C and nitrogen (N) (and the lowest C/N ratio). Sediment accretion rates, belowground biomass (over 1370 days), and C and N concentrations differed significantly between seedling densities. Fine roots were significantly greater compared to medium and coarse roots across all plantation densities. Sulphur and carbon stable isotopes did not vary significantly between different density treatments. Isotope signatures suggest surface sediment C (to a depth of 1 cm) is not derived predominantly from the trees, but from seagrass adjacent to the site.

  7. Competitive Effects of Merger Remedies in Europe’s High-Tech Industry

    NARCIS (Netherlands)

    Angelov, P.A.|info:eu-repo/dai/nl/35720865X; Rosenkranz, S.|info:eu-repo/dai/nl/157222241; Schenk, E.J.J.|info:eu-repo/dai/nl/074056344

    2012-01-01

    Using an event study methodology, this paper assesses the competitive effects of remedies implemented by the European Commission in 11 horizontal mergers in the ICT industry between 1990 and 2010. The estimates of merger announcement effects for both merging parties and competitors have

  8. Effects of Competitive and Cooperative Learning Strategies on Academic Performance of Nigerian Students in Mathematics

    Science.gov (United States)

    Kolawole, E. B.

    2008-01-01

    This study investigated the effects of the cooperative and competitive learning on academic performance of students in mathematics in order to find out which one of them is the more effective learning strategy. The sample of the study was 400 Senior Secondary Schools III, Mathematics students made up of 240 boys and 160 girls randomly selected…

  9. Above and belowground connections and species interactions: Controls over ecosystem fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, Amy Marie [Montana State Univ., Bozeman, MT (United States); Phillips, Richard [Indiana Univ., Bloomington, IN (United States); Stoy, Paul Christopher [Montana State Univ., Bozeman, MT (United States)

    2016-11-01

    season. This research lays the foundation to answer important questions regarding the impacts of seasonality and forest composition on belowground volatile source-sink dynamics in mediating nutrient cycling and biogeochemistry dynamics—critical components of overall ecosystem functioning. In collaboration with the Environmental Simulations Unit (EUS) at the Helmholtz Zentrum in Munich, Germany (headed by Prof. Dr. Joerg-Peter Schinitzler), we investigated carbon investment in above and belowground plant volatile compounds in response to environmental conditions and mycorrhizal associations. Using the sophisticated phytotron facility and on-line trace gas instruments, we conducted controlled laboratory experiments that showed that biotic stresses, such as herbivore feeding, can alter the magnitude of belowground volatile emissions as well as carbon allocation towards these volatiles. We saw no effect of mycorrhizae on any induced response, suggesting that microbial effects were unrelated to source-sink dynamics driving terpene emissions. Furthermore, the results suggest that even though enzyme activity responsible for root volatile synthesis is up-regulated following herbivory, the sink strength of the soil can significantly impact what is measured at the soil/atmosphere interface and thereby what enters the atmosphere. This is important as scientists may be underestimating the magnitude of belowground volatile emissions and their influence on belowground interactions due to limitations associated with current sampling techniques. These key findings are being integrated with results from a hydroxyl radical reactivity-VOC campaign and a late season litter removal experiment to offer a comprehensive mechanistic understanding of the sources and controls over soil volatile emissions, particularly during times of the year when vegetative aboveground emissions are low (leaf senescence). Ultimately, these coupled field and laboratory experiments offer insights into seasonal

  10. Effects of inbreeding and genetic modification on Aedes aegypti larval competition and adult energy reserves

    Directory of Open Access Journals (Sweden)

    Kormaksson Matthias

    2010-10-01

    Full Text Available Abstract Background Genetic modification of mosquitoes offers a promising strategy for the prevention and control of mosquito-borne diseases. For such a strategy to be effective, it is critically important that engineered strains are competitive enough to serve their intended function in population replacement or reduction of wild mosquitoes in nature. Thus far, fitness evaluations of genetically modified strains have not addressed the effects of competition among the aquatic stages and its consequences for adult fitness. We therefore tested the competitive success of combinations of wild, inbred and transgenic (created in the inbred background immature stages of the dengue vector Aedes aegypti in the presence of optimal and sub-optimal larval diets. Results The wild strain of Ae. aegypti demonstrated greater performance (based on a composite index of survival, development rate and size than the inbred strain, which in turn demonstrated greater performance than the genetically modified strain. Moreover, increasing competition through lowering the amount of diet available per larva affected fitness disproportionately: transgenic larvae had a reduced index of performance (95-119% compared to inbred (50-88% and wild type larvae (38-54%. In terms of teneral energy reserves (glycogen, lipid and sugar, adult wild type mosquitoes had more reserves directly available for flight, dispersal and basic metabolic functions than transgenic and inbred mosquitoes. Conclusions Our study provides a detailed assessment of inter- and intra-strain competition across aquatic stages of wild type, inbred, and transgenic mosquitoes and the impact of these conditions on adult energy reserves. Although it is not clear what competitive level is adequate for success of transgenic strains in nature, strong gene drive mechanisms are likely to be necessary in order to overcome competitive disadvantages in the larval stage that carryover to affect adult fitness.

  11. Commercial secret as an instrument of company competitive strategy effectiveness increase

    Directory of Open Access Journals (Sweden)

    Peskova Dinara

    2017-01-01

    Full Text Available Modern companies are very much diversified in scale, sectoral affiliation, marketing behavior. There are many theoretical and applied studies in effective competitiveness strategies (see Porter, M. (2002, 1998, Kramer, M. (1998, Fatkhutdinov, R. A. (2000, Feigelson, V. M. (1996 and others.They present famous approaches and probably there is no need to repeat them in this article. We would like to feature a different concept (suggested by Yudanov A. and followers with terminology adopted from natural sciences and show the way the commercial secret can increase effectiveness of competitiveness strategy. We also perform valid methods of commercial secret protection.

  12. Incorporating network effects in a competitive electricity industry. An Australian perspective

    International Nuclear Information System (INIS)

    Outhred, H.; Kaye, J.

    1996-01-01

    The role of an electricity network in a competitive electricity industry is reviewed, the nation's experience with transmission pricing is discussed, and a 'Nodal Auction Model' for incorporating network effects in a competitive electricity industry is proposed. The model uses a computer-based auction procedure to address both the spatial issues associated with an electricity network and the temporal issues associated with operation scheduling. The objective is to provide a market framework that addresses both network effects and operation scheduling in a coordinated implementation of spot pricing theory. 12 refs

  13. The importance of aboveground–belowground interactions on the evolution and maintenance of variation in plant defense traits

    Science.gov (United States)

    van Geem, Moniek; Gols, Rieta; van Dam, Nicole M.; van der Putten, Wim H.; Fortuna, Taiadjana; Harvey, Jeffrey A.

    2013-01-01

    Over the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground–belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite ecosystem compartments. Less is known about genetic variation in plant traits such as defense as that may be driven by above- and belowground trophic interactions. For instance, although our understanding of genetic variation in aboveground plant traits and its effects on community-level interactions is well developed, little is known about the importance of aboveground–belowground interactions in driving this variation. Plant traits may have evolved in response to selection pressures from above- and below-ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, multiple attacks by antagonists in both domains may lead to trade-offs. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top–down control. At larger scales these interactions may generate evolutionary “hotspots” where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed. PMID:24348484

  14. The spillover effects of affirmative action on competitiveness and unethical behavior

    DEFF Research Database (Denmark)

    Gupta, Nabanita Datta; Banerjee, Ritwik; Villeval, Marie Claire

    2018-01-01

    , and b) whether having been exposed to the policy generates unethical behavior and spite against subjects from the category who has benefited from the policy. We find that this policy substantially increases the beliefs on being a winner and the competitiveness of the backward caste members. However, we......We conduct an artefactual field experiment to examine various spillover effects of Affirmative Action policies in the context of castes in India. We test a) if individuals who enter tournaments in the presence of an Affirmative Action policy remain competitive after the policy has been removed...... find no spillover effect on confidence and competitiveness once Affirmative Action is withdrawn. Furthermore, the discrimination by the dominant category against the backward category is not significantly aggravated by Affirmative Action, except when individuals learn that they have lost the previous...

  15. The Spillover Effects of Affirmative Action on Competitiveness and Unethical Behavior

    DEFF Research Database (Denmark)

    Banerjee, Ritwik; Gupta, Nabanita Datta; Villeval, Marie Claire

    We conduct an artefactual field experiment to examine various spillover effects of Affirmative Action policies in the context of castes in India. We test a) if individuals who compete in the presence of Affirmative Action policies remain competitive in the same proportion after the policy has been...... removed, and b) whether having been exposed to the policy generates unethical behavior and spite against subjects from the category who has benefited from the policy. We find that these policies increase substantially the confidence of the lower caste members and motivate them to choose significantly more...... frequently a tournament payment scheme. However, we find no spillover effect on confidence and competitiveness once Affirmative Action is withdrawn: any lower caste’s gain in competitiveness due to the policy is then entirely wiped out. Furthermore, the strong existing bias of the dominant caste against...

  16. The Detrimental Effects of Oxytocin-Induced Conformity on Dishonesty in Competition.

    Science.gov (United States)

    Aydogan, Gökhan; Jobst, Andrea; D'Ardenne, Kimberlee; Müller, Norbert; Kocher, Martin G

    2017-06-01

    Justifications may promote unethical behavior because they constitute a convenient loophole through which people can gain from immoral behavior and preserve a positive self-image at the same time. A justification that is widely used is rooted in conformity: Unethical choices become more permissible because one's peers are expected to make the same unethical choices. In the current study, we tested whether an exogenous alteration of conformity led to a lower inclination to adhere to a widely accepted norm (i.e., honesty) under the pressure of competition. We took advantage of the well-known effects of intranasally applied oxytocin on affiliation, in-group conformity, and in-group favoritism in humans. We found that conformity was enhanced by oxytocin, and this enhancement had a detrimental effect on honesty in a competitive environment but not in a noncompetitive environment. Our findings contribute to recent evidence showing that competition may lead to unethical behavior and erode moral values.

  17. Co-evolution of the brand effect and competitiveness in evolving networks

    International Nuclear Information System (INIS)

    Guo Jin-Li

    2014-01-01

    The principle that ‘the brand effect is attractive’ underlies the preferential attachment. Here we show that the brand effect is just one dimension of attractiveness. Another dimension is competitiveness. We firstly introduce a general framework that allows us to investigate the competitive aspect of real networks, instead of simply preferring popular nodes. Our model accurately describes the evolution of social and technological networks. The phenomenon that more competitive nodes become richer can help us to understand the evolution of many competitive systems in nature and society. In general, the paper provides an explicit analytical expression of degree distributions of the network. In particular, the model yields a nontrivial time evolution of nodes' properties and the scale-free behavior with exponents depending on the microscopic parameters characterizing the competition rules. Secondly, through theoretical analyses and numerical simulations, we reveal that our model has not only the universality for the homogeneous weighted network, but also the character for the heterogeneous weighted network. Thirdly, we also develop a model based on the profit-driven mechanism. It can better describe the observed phenomenon in enterprise cooperation networks. We show that the standard preferential attachment, the growing random graph, the initial attractiveness model, the fitness model, and weighted networks can all be seen as degenerate cases of our model. (general)

  18. Co-evolution of the brand effect and competitiveness in evolving networks

    Science.gov (United States)

    Guo, Jin-Li

    2014-07-01

    The principle that ‘the brand effect is attractive’ underlies the preferential attachment. Here we show that the brand effect is just one dimension of attractiveness. Another dimension is competitiveness. We firstly introduce a general framework that allows us to investigate the competitive aspect of real networks, instead of simply preferring popular nodes. Our model accurately describes the evolution of social and technological networks. The phenomenon that more competitive nodes become richer can help us to understand the evolution of many competitive systems in nature and society. In general, the paper provides an explicit analytical expression of degree distributions of the network. In particular, the model yields a nontrivial time evolution of nodes' properties and the scale-free behavior with exponents depending on the microscopic parameters characterizing the competition rules. Secondly, through theoretical analyses and numerical simulations, we reveal that our model has not only the universality for the homogeneous weighted network, but also the character for the heterogeneous weighted network. Thirdly, we also develop a model based on the profit-driven mechanism. It can better describe the observed phenomenon in enterprise cooperation networks. We show that the standard preferential attachment, the growing random graph, the initial attractiveness model, the fitness model, and weighted networks can all be seen as degenerate cases of our model.

  19. Effects of competitive learning tools on medical students: A case study

    Science.gov (United States)

    2018-01-01

    Objective Competitive learning techniques are being successfully used in courses of different disciplines. However, there is still a significant gap in analyzing their effects in medical students competing individually. The authors conducted this study to assess the effectiveness of the use of a competitive learning tool on the academic achievement and satisfaction of medical students. Methods The authors collected data from a Human Immunology course in medical students (n = 285) and conducted a nonrandomized (quasi-experimental) control group pretest-posttest design. They used the Mann-Whitney U-test to measure the strength of the association between two variables and to compare the two student groups. Results The improvement and academic outcomes of the experimental group students were significantly higher than those of the control group students. The students using the competitive learning tool had better academic performance, and they were satisfied with this type of learning. The study, however, had some limitations. The authors did not make a random assignment to the control and experimental groups and the groups were not completely homogenous. Conclusion The use of competitive learning techniques motivates medical students, improves their academic outcomes and may foster the cooperation among students and provide a pleasant classroom environment. The authors are planning further studies with a more complete evaluation of cognitive learning styles or incorporating chronometry as well as team-competition. PMID:29518123

  20. Plant life history and above–belowground interactions

    NARCIS (Netherlands)

    Deyn, de Gerlinde

    2017-01-01

    The importance of above–belowground interactions for plant growth and community dynamics became clear in the last decades, whereas the numerous studies on plant life history improved our knowledge on eco-evolutionary dynamics. However, surprisingly few studies have linked both research fields

  1. Empirical and theoretical challenges in aboveground–belowground ecology

    NARCIS (Netherlands)

    Van der Putten, W.H.; Bardgett, R.D.; de Ruiter, P.C.; Hol, W.H.G.; Meyer, K.M.; Bezemer, T.M.; Bradford, M.A.; Christensen, S.; Eppinga, M.B.; Fukami, T.; Hemerik, L.; Molofsky, J.; Schädler, M.; Scherber, C.; Strauss, S.Y.; Vos, M.; Wardle, D.A.

    2009-01-01

    A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from

  2. Empirical and theoretical challenges in aboveground-belowground ecology

    NARCIS (Netherlands)

    Putten, van der W.H.; Bardgett, R.D.; Ruiter, de P.C.; Hol, W.H.G.; Meyer, K.M.; Bezemer, T.M.; Bradford, M.A.; Christensen, S.; Eppinga, M.B.; Fukami, T.; Hemerik, L.; Molofsky, J.; Schädler, M.; Scherber, C.; Strauss, S.Y.; Vos, M.; Wardle, D.A.

    2009-01-01

    A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from

  3. Potential remobilization of belowground permafrost carbon under future global warming

    Science.gov (United States)

    P. Kuhry; E. Dorrepaal; G. Hugelius; E.A.G. Schuur; C. Tarnocai

    2010-01-01

    Research on permafrost carbon has dramatically increased in the past few years. A new estimate of 1672 Pg C of belowground organic carbon in the northern circumpolar permafrost region more than doubles the previous value and highlights the potential role of permafrost carbon in the Earth System. Uncertainties in this new estimate remain due to relatively few available...

  4. Competition between elastic and chemical effects in the intermixing ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. We have performed ab initio density functional theory calculations to investigate the forma- tion energy and the effects of low dimensionality and reduced coordination on the magnetic properties of pseudomorphically grown monolayers of Co–Ag surface alloys on a Rh(111) substrate. We find that if such an alloy ...

  5. The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition.

    Science.gov (United States)

    Marlowe, Frank W; Berbesque, J Colette

    2012-12-01

    Among mammals, male-male competition for sexual access to females frequently involves fighting. Larger body size gives males an advantage in fighting, which explains why males tend to be larger than females in many species, including anthropoid primates. Mitani et al. derived a formula to measure the operational sex ratio (OSR) to reflect the degree of male-male competition using the number of reproductively available males to females who are cycling and capable of conceiving. The OSR should predict the degree of sexual dimorphism in body mass-at least if male-male competition involves much fighting or threatening. Here, we use hunter-gatherer demographic data and the Mitani et al. formula to calculate the human OSR. We show that humans have a much lower degree of body mass sexual dimorphism than is predicted by our OSR. We suggest this is because human competition rarely involves fighting. In human hunter-gatherer societies, differences in the ages of marriage have an impact on competition in that the age of males at first marriage is younger when there is a lower percentage of married men with two or more wives, and older when there is a higher percentage of married men with two or more wives. We discuss the implications of this for females, along with the effects of two key life history traits that influence the OSR, concealed ovulation and menopause. While menopause decreases the number of reproductively available females to males and thus increases male-male competition, concealed ovulation decreases male-male competition. Finally, we discuss the importance of mostly monogamous mate bonds in human evolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Effects of asymmetric medical insurance subsidy on hospitals competition under non-price regulation.

    Science.gov (United States)

    Wang, Chan; Nie, Pu-Yan

    2016-11-15

    Poor medical care and high fees are two major problems in the world health care system. As a result, health care insurance system reform is a major issue in developing countries, such as China. Governments should take the effect of health care insurance system reform on the competition of hospitals into account when they practice a reform. This article aims to capture the influences of asymmetric medical insurance subsidy and the importance of medical quality to patients on hospitals competition under non-price regulation. We establish a three-stage duopoly model with quantity and quality competition. In the model, qualitative difference and asymmetric medical insurance subsidy among hospitals are considered. The government decides subsidy (or reimbursement) ratios in the first stage. Hospitals choose the quality in the second stage and then support the quantity in the third stage. We obtain our conclusions by mathematical model analyses and all the results are achieved by backward induction. The importance of medical quality to patients has stronger influence on the small hospital, while subsidy has greater effect on the large hospital. Meanwhile, the importance of medical quality to patients strengthens competition, but subsidy effect weakens it. Besides, subsidy ratios difference affects the relationship between subsidy and hospital competition. Furthermore, we capture the optimal reimbursement ratio based on social welfare maximization. More importantly, this paper finds that the higher management efficiency of the medical insurance investment funds is, the higher the best subsidy ratio is. This paper states that subsidy is a two-edged sword. On one hand, subsidy stimulates medical demand. On the other hand, subsidy raises price and inhibits hospital competition. Therefore, government must set an appropriate subsidy ratio difference between large and small hospitals to maximize the total social welfare. For a developing country with limited medical resources

  7. Plant competitive interactions and invasiveness: searching for the effects of phylogenetic relatedness and origin on competition intensity

    Czech Academy of Sciences Publication Activity Database

    Dostál, Petr

    2011-01-01

    Roč. 177, č. 5 (2011), s. 655-667 ISSN 0003-0147 R&D Projects: GA ČR GAP504/10/0132 Institutional research plan: CEZ:AV0Z60050516 Keywords : competitive equivalence * invasive plants * phylogenetic similarity Subject RIV: EF - Botanics Impact factor: 4.725, year: 2011

  8. Intergroup competition as a double-edged sword : How sex composition regulates the effects of competition on group creativity

    NARCIS (Netherlands)

    Bear, M.; Abhijeet, K.; Leenders, R.T.A.J.; Oldham, G.R.

    2014-01-01

    Building on social role theory, we extend a contingency perspective on intergroup competition proposing that having groups compete against one another is stimulating to the creativity of groups composed largely or exclusively of men but detrimental to the creativity of groups composed largely or

  9. Larval size in acanthocephalan parasites: Influence of intraspecific competition and effects on intermediate host behavioural changes

    Directory of Open Access Journals (Sweden)

    Dianne Lucile

    2012-08-01

    Full Text Available Abstract Background Parasites often face a trade-off between exploitation of host resources and transmission probabilities to the next host. In helminths, larval growth, a major component of adult parasite fitness, is linked to exploitation of intermediate host resources and is influenced by the presence of co-infecting conspecifics. In manipulative parasites, larval growth strategy could also interact with their ability to alter intermediate host phenotype and influence parasite transmission. Methods We used experimental infections of Gammarus pulex by Pomphorhynchus laevis (Acanthocephala, to investigate larval size effects on host behavioural manipulation among different parasite sibships and various degrees of intra-host competition. Results Intra-host competition reduced mean P. laevis cystacanth size, but the largest cystacanth within a host always reached the same size. Therefore, all co-infecting parasites did not equally suffer from intraspecific competition. Under no intra-host competition (1 parasite per host, larval size was positively correlated with host phototaxis. At higher infection intensities, this relationship disappeared, possibly because of strong competition for host resources, and thus larval growth, and limited manipulative abilities of co-infecting larval acanthocephalans. Conclusions Our study indicates that behavioural manipulation is a condition-dependant phenomenon that needs the integration of parasite-related variables to be fully understood.

  10. Larval size in acanthocephalan parasites: influence of intraspecific competition and effects on intermediate host behavioural changes.

    Science.gov (United States)

    Dianne, Lucile; Bollache, Loïc; Lagrue, Clément; Franceschi, Nathalie; Rigaud, Thierry

    2012-08-09

    Parasites often face a trade-off between exploitation of host resources and transmission probabilities to the next host. In helminths, larval growth, a major component of adult parasite fitness, is linked to exploitation of intermediate host resources and is influenced by the presence of co-infecting conspecifics. In manipulative parasites, larval growth strategy could also interact with their ability to alter intermediate host phenotype and influence parasite transmission. We used experimental infections of Gammarus pulex by Pomphorhynchus laevis (Acanthocephala), to investigate larval size effects on host behavioural manipulation among different parasite sibships and various degrees of intra-host competition. Intra-host competition reduced mean P. laevis cystacanth size, but the largest cystacanth within a host always reached the same size. Therefore, all co-infecting parasites did not equally suffer from intraspecific competition. Under no intra-host competition (1 parasite per host), larval size was positively correlated with host phototaxis. At higher infection intensities, this relationship disappeared, possibly because of strong competition for host resources, and thus larval growth, and limited manipulative abilities of co-infecting larval acanthocephalans. Our study indicates that behavioural manipulation is a condition-dependant phenomenon that needs the integration of parasite-related variables to be fully understood.

  11. Effects of clonal fragmentation on intraspecific competition of a stoloniferous floating plant.

    Science.gov (United States)

    Wang, P; Xu, Y-S; Dong, B-C; Xue, W; Yu, F-H

    2014-11-01

    Disturbance is common and can fragment clones of plants. Clonal fragmentation may affect the density and growth of ramets so that it could alter intraspecific competition. To test this hypothesis, we grew one (low density), five (medium density) or nine (high density) parent ramets of the floating invasive plant Pistia stratiotes in buckets, and newly produced offspring ramets were either severed (with fragmentation) or remained connected to parent ramets (no fragmentation). Increasing density reduced biomass of the whole clone (i.e. parent ramet plus its offspring ramets), showing intense intraspecific competition. Fragmentation decreased biomass of offspring ramets, but increased biomass of parent ramets and the whole clone, suggesting significant resource translocation from parent to offspring ramets when clones were not fragmented. There was no interaction effect of density x fragmentation on biomass of the whole clone, and fragmentation did not affect competition intensity index. We conclude that clonal fragmentation does not alter intraspecific competition between clones of P. stratiotes, but increases biomass production of the whole clone. Thus, fragmentation may contribute to its interspecific competitive ability and invasiveness, and intentional fragmentation should not be recommended as a measure to stop the rapid growth of this invasive species. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  12. Competitive bidding in Medicare Advantage: effect of benchmark changes on plan bids.

    Science.gov (United States)

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

    2013-12-01

    Bidding has been proposed to replace or complement the administered prices that Medicare pays to hospitals and health plans. In 2006, the Medicare Advantage program implemented a competitive bidding system to determine plan payments. In perfectly competitive models, plans bid their costs and thus bids are insensitive to the benchmark. Under many other models of competition, bids respond to changes in the benchmark. We conceptualize the bidding system and use an instrumental variable approach to study the effect of benchmark changes on bids. We use 2006-2010 plan payment data from the Centers for Medicare and Medicaid Services, published county benchmarks, actual realized fee-for-service costs, and Medicare Advantage enrollment. We find that a $1 increase in the benchmark leads to about a $0.53 increase in bids, suggesting that plans in the Medicare Advantage market have meaningful market power. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Effects of disorder on coexistence and competition between superconducting and insulating states

    NARCIS (Netherlands)

    Mostovoy, MV; Marchetti, FM; Simons, BD; Littlewood, PB

    We study effects of nonmagnetic impurities on the competition between the superconducting and electron-hole pairing. We show that disorder can result in coexistence of these two types of ordering in a uniform state, even when in clean materials they are mutually exclusive.

  14. Testing for effects of climate change on competitive relationships and coexistence between two bird species

    NARCIS (Netherlands)

    Stenseth, Nils Chr.; Durant, Joel M.; Fowler, Mike S.; Matthysen, Erik; Adriaensen, Frank; Jonzen, Niclas; Chan, Kung-Sik; Liu, Hai; De Laet, Jenny; Sheldon, Ben C.; Visser, Marcel E.; Dhondt, Andre A.

    2015-01-01

    Climate change is expected to have profound ecological effects, yet shifts in competitive abilities among species are rarely studied in this context. Blue tits (Cyanistes caeruleus) and great tits (Parus major) compete for food and roosting sites, yet coexist across much of their range. Climate

  15. 12 CFR 250.182 - Terms defining competitive effects of proposed mergers.

    Science.gov (United States)

    2010-01-01

    ... mergers. 250.182 Section 250.182 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS... competitive effects of proposed mergers. Under the Bank Merger Act (12 U.S.C. 1828(c)), a Federal Banking agency receiving a merger application must request the views of the other two banking agencies and the...

  16. Water and nutrients alter herbaceous competitive effects on tree seedlings in a semi-arid savanna

    NARCIS (Netherlands)

    Waal, van der C.; Kroon, de H.; Boer, de W.F.; Heitkonig, I.M.A.; Skidmore, A.K.; Knegt, de H.J.; Langevelde, van F.; Wieren, van S.E.; Grant, R.C.; Page, B.R.; Slotow, R.; Kohi, E.; Mwakiwa, E.; Prins, H.H.T.

    2009-01-01

    1. Globally, both climatic patterns and nitrogen deposition rates show directional changes over time. It is uncertain how woody seedlings, which coexist with herbaceous plants in savannas, respond to concurrent changes in water and nutrient availability. 2. We investigated competition effects

  17. Effects of inbreeding and genetic modification on Aedes aegypti larval competition and adult energy reserves

    NARCIS (Netherlands)

    Koenraadt, C.J.M.; Kormaksson, M.; Harrington, L.C.

    2010-01-01

    Background - Genetic modification of mosquitoes offers a promising strategy for the prevention and control of mosquito-borne diseases. For such a strategy to be effective, it is critically important that engineered strains are competitive enough to serve their intended function in population

  18. The Cost-Effectiveness of Anterior Cruciate Ligament Reconstruction in Competitive Athletes.

    Science.gov (United States)

    Stewart, Bruce A; Momaya, Amit M; Silverstein, Marc D; Lintner, David

    2017-01-01

    Competitive athletes value the ability to return to competitive play after the treatment of anterior cruciate ligament (ACL) injuries. ACL reconstruction has high success rates for return to play, but some studies indicate that patients may do well with nonoperative physical therapy treatment. To evaluate the cost-effectiveness of the treatment of acute ACL tears with either initial surgical reconstruction or physical therapy in competitive athletes. Economic and decision analysis; Level of evidence, 2. The incremental cost, incremental effectiveness, and incremental cost-effectiveness ratio (ICER) of ACL reconstruction compared with physical therapy were calculated from a cost-effectiveness analysis of ACL reconstruction compared with physical therapy for the initial management of acute ACL injuries in competitive athletes. The ACL reconstruction strategy and the physical therapy strategy were represented as Markov models. Costs and quality-adjusted life-years (QALYs) were evaluated over a 6-year time horizon and were analyzed from a societal perspective. Quality of life and probabilities of clinical outcomes were obtained from the peer-reviewed literature, and costs were compiled from a large academic hospital in the United States. One-way, 2-way, and probabilistic sensitivity analyses were used to assess the effect of uncertainty in variables on the ICER of ACL reconstruction. The ICER of ACL reconstruction compared with physical therapy was $22,702 per QALY gained. The ICER was most sensitive to the quality of life of returning to play or not returning to play, costs, and duration of follow-up but relatively insensitive to the rates and costs of complications, probabilities of return to play for both operative and nonoperative treatments, and discount rate. ACL reconstruction is a cost-effective strategy for competitive athletes with an ACL injury.

  19. Atmospheric CO2 and O3 alter competition for soil nitrogen in developing forests

    Science.gov (United States)

    Donald R. Zak; Mark E. Kubiske; Kurt S. Pregitzer; Andrew J. Burton

    2012-01-01

    Plant growth responses to rising atmospheric CO2 and O3 vary among genotypes and between species, which could plausibly influence the strength of competitive interactions for soil N. Ascribable to the size-symmetric nature of belowground competition, we reasoned that differential growth responses to CO2...

  20. Untangling above- and belowground mycorrhizal fungal networks in tropical orchids.

    Science.gov (United States)

    Leake, J R; Cameron, D D

    2012-10-01

    Orchids typically depend on fungi for establishment from seeds, forming mycorrhizal associations with basidiomycete fungal partners in the polyphyletic group rhizoctonia from early stages of germination, sometimes with very high specificity. This has raised important questions about the roles of plant and fungal phylogenetics, and their habitat preferences, in controlling which fungi associate with which plants. In this issue of Molecular Ecology, Martos et al. (2012) report the largest network analysis to date for orchids and their mycorrhizal fungi, sampling a total of over 450 plants from nearly half the 150 tropical orchid species on Reunion Island, encompassing its main terrestrial and epiphytic orchid genera. The authors found a total of 95 operational taxonomic units of mycorrhizal fungi and investigated the architecture and nestedness of their bipartite networks with 73 orchid species. The most striking finding was a major ecological barrier between above- and belowground mycorrhizal fungal networks, despite both epiphytic and terrestrial orchids often associating with closely related taxa across all three major lineages of rhizoctonia fungi. The fungal partnerships of the epiphytes and terrestrial species involved a diversity of fungal taxa in a modular network architecture, with only about one in ten mycorrhizal fungi partnering orchids in both groups. In contrast, plant and fungal phylogenetics had weak or no effects on the network. This highlights the power of recently developed ecological network analyses to give new insights into controls on plant-fungal symbioses and raises exciting new hypotheses about the differences in properties and functioning of mycorrhiza in epiphytic and terrestrial orchids. © 2012 Blackwell Publishing Ltd.

  1. Arbuscular mycorrhizal fungi alter above- and below-ground chemical defense expression differentially among Asclepias species

    Directory of Open Access Journals (Sweden)

    Rachel L Vannette

    2013-09-01

    Full Text Available Belowground symbionts of plants can have substantial influence on plant growth and nutrition. Recent work demonstrates that mycorrhizal fungi can affect plant resistance to herbivory and the performance of above and belowground herbivores. Although these examples emerge from diverse systems, it is unclear if plant species that express similar defensive traits respond similarly to fungal colonization, but comparative work may inform this question. To examine the effects of arbuscular mycorrhizal fungi (AMF on the expression of chemical resistance, we inoculated 8 species of Asclepias (milkweed--which all produce toxic cardenolides--with a community of AMF. We quantified plant biomass, foliar and root cardenolide concentration and composition, and assessed evidence for a growth-defense tradeoff in the presence and absence of AMF. As expected, total foliar and root cardenolide concentration varied among milkweed species. Importantly, the effect of mycorrhizal fungi on total foliar cardenolide concentration also varied among milkweed species, with foliar cardenolides increasing or decreasing, depending on the plant species. We detected a phylogenetic signal to this variation; AMF fungi reduced foliar cardenolide concentrations to a greater extent in the clade including A. curassavica than in the clade including A. syriaca. Moreover, AMF inoculation shifted the composition of cardenolides in above- and below-ground plant tissues in a species-specific fashion. Mycorrhizal inoculation changed the relative distribution of cardenolides between root and shoot tissue in a species-specific fashion, but did not affect cardenolide diversity or polarity. Finally, a tradeoff between plant growth and defense in non-mycorrhizal plants was mitigated completely by AMF inoculation. Overall, we conclude that the effects of AMF inoculation on the expression of chemical resistance can vary among congeneric plant species, and ameliorate tradeoffs between growth and

  2. Effect of Black Economic Empowerment on profit and competitiveness of firms in South Africa

    Directory of Open Access Journals (Sweden)

    Ewert P.J. Kleynhans

    2014-07-01

    Full Text Available Orientation: The key obstacle hindering optimal profitability levels and competitiveness in firms in South Africa is the application of labour legislation policies and tools aimed at narrowing the income gap between different racial groups and resolving inequality amongst a diverse workforce. Research purpose: This article determined whether the implementation of a Black Economic Empowerment (BEE policy by companies has a positive effect on their growth in terms of profits and competitiveness. Motivation for the study: This study determined whether the implementation of BEE could be profitable for companies. Research design, approach and method: A quantitative study was undertaken in order to find empirical evidence supporting the relation between high BEE Scores, profitability and competitiveness. The empirical investigation utilised regression analysis, correlations and other methods, based on data between January 2009 and December 2011. The BEE Scorecard was used to obtain BEE scores of the top 50 BEE companies. Thereafter, the top 50 companies’ financial information was gathered from the Johannesburg Securities Exchange. Main findings: The implementation of BEE within companies has a positive effect on profitability, turnover and investment. Numerous factors have, however, been hindering,while other factors enhanced the success of BEE. Practical/managerial implications: The findings encourage mangers to engage in BEE as it may facilitate higher profits and indicates where labour legislation could be improved. Contribution/value-add: Value was added through new research determining the effects of BEE and labour legislation on profitability and competitiveness of firms on a micro-level.

  3. Effects of competition and facilitation on species assemblage in two types of tropical cloud forest.

    Directory of Open Access Journals (Sweden)

    Wenxing Long

    Full Text Available Competition and facilitation between tree individuals are two kinds of non-random processes influencing the structure and functioning of forest communities, but how these two plant-plant interactions change along gradient of resources or environments remains very much a matter of debate. We developed a null model to test the size-distance regression, and assessed the effects of competition and facilitation (including interspecific interactions, intraspecific interactions and overall species interactions on each adult tree species assemblage [diameter at breast height (dbh ≥5 cm] across two types of tropical cloud forest with different environmental and resource regimes. The null model test revealed that 17% to 27% tree species had positive dbh-distance correlations while 11% to 19% tree species showed negative dbh-distance correlations within these two forest types, indicating that both competition and facilitation processes existed during the community assembly. The importance of competition for heterospecific species, and the intensity of competition for both heterospecific and overall species increased from high to low resources for all the shared species spanning the two forests. The importance of facilitation for conspecific and overall species, as well as that the intensity of facilitation for both heterospecific and conspecific species increased with increasing low air temperature stress for all the shared species spanning the two forests. Our results show that both competition and facilitation processes simultaneously affect parts of species assemblage in the tropical cloud forests. Moreover, the fact that nearly 50% species assemblage is not detected with our approaches suggest that tree species in these tropical forest systems are assembled with multiple ecological processes, and that there is a need to explore the processes other than the two biotic interactions in further researches.

  4. Warming effects on consumption and intraspecific interference competition depend on predator metabolism.

    Science.gov (United States)

    Lang, Birgit; Rall, Björn C; Brose, Ulrich

    2012-05-01

    1. Model analyses show that the stability of population dynamics and food web persistence increase with the strength of interference competition. Despite this critical importance for community stability, little is known about how external factors such as the environmental temperature affect intraspecific interference competition. 2. We aimed to fill this void by studying the functional responses of two ground beetle species of different body size, Pterostichus melanarius and Poecilus versicolor. These functional response experiments were replicated across four predator densities and two temperatures to address the impact of temperature on intraspecific interference competition. 3. We generally expected that warming should increase the speed of movement, encounter rates and in consequence interference among predator individuals. In our experiment, this expectation was supported by the results obtained for the larger predator, P. melanarius, whereas the opposite pattern characterized the interference behaviour of the smaller predator P. versicolor. 4. These results suggest potentially nontrivial implications for the effects of environmental temperature on intraspecific interference competition, for which we propose an explanation based on the different sensitivity to warming of metabolic rates of both species. As expected, increasing temperature led to stronger interference competition of the larger species, P. melanarius, which exhibited a weaker increase in metabolic rate with increasing temperature. The stronger increase in the metabolic rate of the smaller predator, P. versicolor, had to be compensated by increasing searching activity for prey, which did not leave time for increasing interference. 5. Together, these results suggest that any generalization how interference competition responds to warming should also take the species' metabolic response to temperature increases into account. © 2011 The Authors. Journal of Animal Ecology © 2011

  5. Effects of Competition and Facilitation on Species Assemblage in Two Types of Tropical Cloud Forest

    Science.gov (United States)

    Long, Wenxing; Zang, Runguo; Ding, Yi; Huang, Yunfeng

    2013-01-01

    Competition and facilitation between tree individuals are two kinds of non-random processes influencing the structure and functioning of forest communities, but how these two plant-plant interactions change along gradient of resources or environments remains very much a matter of debate. We developed a null model to test the size-distance regression, and assessed the effects of competition and facilitation (including interspecific interactions, intraspecific interactions and overall species interactions) on each adult tree species assemblage [diameter at breast height (dbh) ≥5 cm] across two types of tropical cloud forest with different environmental and resource regimes. The null model test revealed that 17% to 27% tree species had positive dbh-distance correlations while 11% to 19% tree species showed negative dbh-distance correlations within these two forest types, indicating that both competition and facilitation processes existed during the community assembly. The importance of competition for heterospecific species, and the intensity of competition for both heterospecific and overall species increased from high to low resources for all the shared species spanning the two forests. The importance of facilitation for conspecific and overall species, as well as that the intensity of facilitation for both heterospecific and conspecific species increased with increasing low air temperature stress for all the shared species spanning the two forests. Our results show that both competition and facilitation processes simultaneously affect parts of species assemblage in the tropical cloud forests. Moreover, the fact that nearly 50% species assemblage is not detected with our approaches suggest that tree species in these tropical forest systems are assembled with multiple ecological processes, and that there is a need to explore the processes other than the two biotic interactions in further researches. PMID:23565209

  6. The Interdependence of Competition Policy, Consumer Policy and Regulation in Introducing and Safeguarding Effective Competition in the EU Telecommunications Market

    OpenAIRE

    Bartels, Andreas; Pleșea, Doru Alexandru; Studeny, Michael; Just, Vanessa

    2017-01-01

    Currently, the European Union finds itself in troubled waters. It has to prove that its benefits outweigh the costs of its endeavour. In this respect, an EU competition policy that focuses on consumer welfare is one way to gain support by the citizens of its member states. The Roaming Regulation that has reduced the mobile communications costs while travelling abroad serves as a good example for this approach. The EU Commission views consumer policy as another important factor to protect and ...

  7. The effects of relaxing music for anxiety control on competitive sport anxiety.

    Science.gov (United States)

    Elliott, Dave; Polman, Remco; Taylor, Julie

    2014-01-01

    This investigation examined the effects of relaxing music for anxiety control on measures of competitive state anxiety and the performance of a simple motor skill. Seventy-two undergraduate students volunteered to participate in the study. Participants were informed that they would be required to partake in a sport competition, possibly with an audience present, and possibly whilst being filmed. Participants were randomly allocated to one of three intervention conditions, listening to relaxing music for anxiety control, listening to non-relaxing music or a no music control. During the 10-minute intervention period, measures of anxiety (CSAI-2R, subjective relaxation and HR) were taken on three occasions (baseline, pre-intervention and post-intervention). Repeated measures MANOVA showed that all three interventions provoked significant reductions in competitive state anxiety. Condition had no impact upon any of the DVs. These results suggest that listening to relaxing music for anxiety control was no more effective at reducing competitive state anxiety than non-relaxing music or a period of silence. ES, mean difference and 90% CI data did however provide some support for the application of relaxing music for anxiety control. There were no between-condition differences in motor task performance.

  8. Testing for effects of climate change on competitive relationships and coexistence between two bird species.

    Science.gov (United States)

    Stenseth, Nils Chr; Durant, Joël M; Fowler, Mike S; Matthysen, Erik; Adriaensen, Frank; Jonzén, Niclas; Chan, Kung-Sik; Liu, Hai; De Laet, Jenny; Sheldon, Ben C; Visser, Marcel E; Dhondt, André A

    2015-05-22

    Climate change is expected to have profound ecological effects, yet shifts in competitive abilities among species are rarely studied in this context. Blue tits (Cyanistes caeruleus) and great tits (Parus major) compete for food and roosting sites, yet coexist across much of their range. Climate change might thus change the competitive relationships and coexistence between these two species. Analysing four of the highest-quality, long-term datasets available on these species across Europe, we extend the textbook example of coexistence between competing species to include the dynamic effects of long-term climate variation. Using threshold time-series statistical modelling, we demonstrate that long-term climate variation affects species demography through different influences on density-dependent and density-independent processes. The competitive interaction between blue tits and great tits has shifted in one of the studied sites, creating conditions that alter the relative equilibrium densities between the two species, potentially disrupting long-term coexistence. Our analyses show that long-term climate change can, but does not always, generate local differences in the equilibrium conditions of spatially structured species assemblages. We demonstrate how long-term data can be used to better understand whether (and how), for instance, climate change might change the relationships between coexisting species. However, the studied populations are rather robust against competitive exclusion. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Weed-crop competition effects on growth and yield of sugarcane planted using two methods

    International Nuclear Information System (INIS)

    Zafar, M.; Tanveer, A.; Cheema, Z.A.; Ashraf, M.

    2010-01-01

    Effect of planting techniques and weed-crop competition periods on yield potential of spring planted sugarcane variety HSF-240 was studied at the Ayub Agricultural Research Institute, Faisalabad, Pakistan. The experiment was laid out in RCBD with a split-plot arrangement, with four replications and net plot size of 3.6m x 10m. In the experiment, two planting techniques viz., 60 cm apart rows in flat sowing technique and 120 cm apart rows in trench sowing technique were randomized in main plots. Seven weed-crop competition periods viz., Zero (weed free), weed-crop competition for 45, 60, 75, 90, 105 days after sowing (DAS) and weedy check (full season weed-crop competition) were randomized in sub-plots. Sugarcane sown by trench method exhibited more leaf area index (LAI), average crop growth rate (ACGR) and yield contributing attributes. Trench sowing by yielding 72.22 and 75.08 t ha/sup -1/ stripped cane yields, significantly showed superiority over the flat sowing, which gave 64.13 and 66.04 t ha/sup -1/ stripped cane yields in 2005-06 and 2006- 07, respectively. Generally, there was an increase in weed population and biomass but decrease in leaf area index, crop growth rate and yield components with an increase in weed-crop competition period. A decrease of 10.06, 17.90, 22.42, 28.65, 37.64 and 56.89% in stripped cane yield was observed for weed-crop competition periods of 45, 60, 75, 90, 105 DAS and weedy check as compared with zero competition in 2005-06, respectively. In 2006-07, the respective decrease in stripped cane yield was 9.84, 18.76, 22.92, 27.98, 38.75, and 54.98%. Trench sowing at 1.2 m row spacing proved better sowing technique and 45 DAS was the critical period of weed-crop competition. (author)

  10. Effects of soil nutrient heterogeneity on intraspecific competition in the invasive, clonal plant Alternanthera philoxeroides.

    Science.gov (United States)

    Zhou, Jian; Dong, Bi-Cheng; Alpert, Peter; Li, Hong-Li; Zhang, Ming-Xiang; Lei, Guang-Chun; Yu, Fei-Hai

    2012-03-01

    Fine-scale, spatial heterogeneity in soil nutrient availability can increase the growth of individual plants, the productivity of plant communities and interspecific competition. If this is due to the ability of plants to concentrate their roots where nutrient levels are high, then nutrient heterogeneity should have little effect on intraspecific competition, especially when there are no genotypic differences between individuals in root plasticity. We tested this hypothesis in a widespread, clonal species in which individual plants are known to respond to nutrient heterogeneity. Plants derived from a single clone of Alternanthera philoxeroides were grown in the greenhouse at low or high density (four or 16 plants per 27·5 × 27·5-cm container) with homogeneous or heterogeneous availability of soil nutrients, keeping total nutrient availability per container constant. After 9 weeks, measurements of size, dry mass and morphology were taken. Plants grew more in the heterogeneous than in the homogeneous treatment, showing that heterogeneity promoted performance; they grew less in the high- than in the low-density treatment, showing that plants competed. There was no interactive effect of nutrient heterogeneity and plant density, supporting the hypothesis that heterogeneity does not affect intraspecific competition in the absence of genotypic differences in plasticity. Treatments did not affect morphological characteristics such as specific leaf area or root/shoot ratio. Results indicate that fine-scale, spatial heterogeneity in the availability of soil nutrients does not increase competition when plants are genetically identical, consistent with the suggestion that effects of heterogeneity on competition depend upon differences in plasticity between individuals. Heterogeneity is only likely to increase the spread of monoclonal, invasive populations such as that of A. philoxeroides in China.

  11. The effects of competition and implicit power motive on men's testosterone, emotion recognition, and aggression.

    Science.gov (United States)

    Vongas, John G; Al Hajj, Raghid

    2017-06-01

    A contribution to a special issue on Hormones and Human Competition. We investigated the effects of competition on men's testosterone levels and assessed whether androgen reactivity was associated with subsequent emotion recognition and reactive and proactive aggression. We also explored whether personalized power (p Power) moderated these relationships. In Study 1, 84 males competed on a number tracing task and interpreted emotions from facial expressions. In Study 2, 72 males competed on the same task and were assessed on proactive and reactive aggression. In both studies, contrary to the biosocial model of status (Mazur, 1985), winners' testosterone levels decreased significantly while losers' levels increased, albeit not significantly. Personalized power moderated the effect of competition outcome on testosterone change in both studies. Using the aggregate sample, we found that the effect of decreased testosterone levels among winners (compared to losers) was significant for individuals low in p Power but not for those with medium or high p Power. Testosterone change was positively related to emotion recognition, but unrelated to either aggression subtype. The testosterone-mediated relationship between winning and losing and emotion recognition was moderated by p Power. In addition, p Power moderated the direct (i.e., non-testosterone mediated) path between competition outcome and emotion recognition and both types of aggression: high p-Power winners were more accurate at deciphering others' emotions than high p-Power losers. Finally, among high p-Power men, winners aggressed more proactively than losers, whereas losers aggressed more reactively than winners. Collectively, these studies highlight the importance of implicit power motivation in modulating hormonal, cognitive, and behavioral outcomes arising from human competition. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. The effects of the intake of an isotonic sports drink before orienteering competitions on skeletal muscle damage.

    Science.gov (United States)

    Colakoglu, Filiz Fatma; Cayci, Banu; Yaman, Metin; Karacan, Selma; Gonulateş, Suleyman; Ipekoglu, Gökhan; Er, Fatmanur

    2016-11-01

    [Purpose] The purpose of this study was to investigate the effects of the intake of an isotonic sports drink (500 ml water, 32 gr carbonhydrate, 120 mg calcium, 248 mg chloride, 230 mg sodium) the level of the skeletal muscle damage of orienteering athletes. [Subjects and Methods] The study was carried out on 21 male elite orienteering athletes. The athletes were divided into two groups by randomized double-blind selection. The experimental group (n=11) was given the isotonic sports drink, while the placebo group (n=10) was given 500 ml pure water. Blood samples were taken pre-competition, post-competition, 2 hours post-competition and 24 hours post-competition. [Results] The pre-c troponin, myoglobin and creatinine kinase serum levels of the placebo group were significantly lower than the post-competition and 2 hours post-competition values. The 24 hours post-competition levels of the same analyses were also significantly lower than the post-c and 2 hours post-competition. The pre-competition troponin, myoglobin and creatinine kinase levels of the experimental group were found to be significantly lower than the post-competition, 2 hours post-competition 24 hours post-competition values. In conclusion, the present results suggest that the intake of supportive sports drinks before exercising significantly prevents the observed muscle damage. The study showed that serum myoglobin levels between the experimental and the placebo group is significantly different during the 2 hours post-competition period. [Conclusion] The level of serum creatinine kinase and myoglobin accurately shows the extent of the muscle damage. However, further studies on the effect of isotonic sports drink in different training programs on the cell membrane and the muscle damage are needed.

  13. The Dual Effects of Intellectual Property Regulations: Within- and Between-Patent Competition in the U.S. Pharmaceuticals Industry

    OpenAIRE

    Frank R. Lichtenberg; Tomas J. Philipson

    2002-01-01

    A patent only protects an innovator from others producing the same product, but it does not protect him from others producing better products under new patents. Therefore, one may divide up the source of competition facing an innovator into within-patent competition, which results from production of the same product, and betweenpatent competition, which results from production of products on other patents. Previous theoretical and empirical micro -based analyses have emphasized the effects of...

  14. Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

    International Nuclear Information System (INIS)

    Lu, Yan; Wei, Sheng; Jin, Jing; Wang, Li; Lu, Wengang

    2016-01-01

    We explore the electronic properties and exciton effects in short graphene nanoribbons (SGNRs), which have two armchair edges and two zigzag edges. Our results show that both of these two types of edges have profound effects on the electronic properties and exciton effects. Both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) states are alternatively changed between the bulk and the edge states as the lengths of the zigzag edges increase, due to the competition between the states of the two types of edges. The energy gaps, as a function of the lengths of the armchair edges, will then induce two kinds of trends. Furthermore, two kinds of exciton energies and exciton binding energies are found, which can be understood through the two kinds of HOMO and LUMO states in SGNRs. In addition, we find that the three triplet exciton states are not totally energy degenerate in SGNRs due to the spin-polarized states on the zigzag edges. (paper)

  15. Assembled Products: The Key to More Effective Competition And Antitrust Oversight in Health Care.

    Science.gov (United States)

    Sage, William M

    2016-01-01

    This Article argues that recent calls for antitrust enforcement to protect health insurers from hospital and physician consolidation are incomplete. The principal obstacle to effective competition in health care is not that one or the other party has too much bargaining power, but that they have been buying and selling the wrong things. Vigorous antitrust enforcement will benefit health care consumers only if it accounts for the competitive distortions caused by the sector's long history of government regulation. Because of regulation, what pass for products in health care are typically small process steps and isolated components that can be assigned a billing code, even if they do little to help patients. Instead of further entrenching weakly competitive parties engaged in artificial commerce, antitrust enforcers and regulators should work together to promote the sale of fully assembled products and services that can be warranted to consumers for performance and safety. As better products emerge through innovation and market entry, competition may finally succeed at lowering medical costs, increasing access to treatment, and improving quality of care.

  16. Effect of intraspecific competition and substrate type on terpene emissions from some Mediterranean plant species.

    Science.gov (United States)

    Ormeño, Elena; Bousquet-Mélou, Anne; Mévy, Jean-Philippe; Greff, Stéphane; Robles, Christine; Bonin, Gilles; Fernandez, Catherine

    2007-02-01

    Competition is an important factor that has been extensively reported in the Mediterranean area. There is evidence that leaf terpene accumulation may vary between plants growing on calcareous and siliceous soils. In the present study, leaf terpene emissions from potted seedlings of Pinus halepensis, Cistus albidus, and Quercus coccifera, growing under natural environmental conditions on calcareous and siliceous substrates, were studied by using a bag enclosure method. In both substrates, seedlings were potted alone and in intraspecific competition, to examine the effect of substrate type and that of intraspecific competition on terpene emissions. The results showed that competition favored: (i) overall monoterpene and sesquiterpene emissions from Q. coccifera; (ii) overall monoterpene emissions from P. halepensis; (iii) overall sesquiterpene emissions from C. albidus. Substrate type affected terpene emissions to a limited extent and in a species-specific way. Whereas for Q. coccifera, the overall monoterpene emissions and that of Allo-aromadendrene were favored on siliceous substrate, no significant changes were found in emissions from P. halepensis. Only the release of AR-curcumene from C. albidus was higher on siliceous substrate. We also found high variability in terpene emission composition from the study species, particularly for P. halepensis and Q. coccifera. These two species released both monoterpenes and sesquiterpenes, instead of monoterpenes only, as shown in previous studies.

  17. Multiple infestation by seed predators: the effect of loculate fruits on intraspecific insect larval competition

    Science.gov (United States)

    Serrano, José M.; Delgado, Juan A.; López, Francisco; Acosta, Francisco J.; Fungairiño, Sara G.

    2001-06-01

    Many morphological features of fruits are important factors affecting predispersal seed predation by insects. This paper analyses the predispersal seed predation process of a major predator (a Noctuidae lepidopteran larvae) in loculate fruits of a bushy perennial plant, Cistus ladanifer. The main aim of the study is to assess the potential effect of internal valvae (which partition groups of seeds) in the intraspecific competition between larvae in multiple-infested fruits. Our results show that larvae do not reject already infested fruits, but they avoid the proximity of other larvae within the fruit, keeping an average minimum distance of one locule. In multiple-infested fruits, larval mortality increases and the proportion of seeds consumed by each larvae decreases. In those situations in which valvae keep apart larvae within a fruit, these only suffer the cost of exploitation competition with a low acquisition of resources. However, when all valvae between them are pierced by the larvae, competition switches to an interference component and larval mortality increases markedly. The existence of valvae within a fruit allows larvae to diminish the cost of intraspecific competition, obtaining high life expectancies (70%), even in triple-infested fruits.

  18. The effect of competition on heart rate during kart driving: A field study

    Science.gov (United States)

    2011-01-01

    Background Both the act of competing, which can create a kind of mental stress, and participation in motor sports, which induces physical stress from intense g-forces, are known to increase heart rate dramatically. However, little is known about the specific effect of competition on heart rate during motor sports, particularly during four-wheel car driving. The goal of this preliminary study, therefore, was to investigate whether competition increases heart rate under such situations. Findings The participants drove an entry-level formula kart during two competitive races and during solo driving against the clock while heart rate and g-forces were measured. Analyses showed that heart rate values during the races (168.8 beats/min) were significantly higher than those during solo driving (140.9 beats/min) and rest (75.1 beats/min). Conclusions The results of this preliminary study indicate that competition heightens heart rate during four-wheel car driving. Kart drivers should be concerned about maintaining good health and developing physical strength. PMID:21906298

  19. Variability in above- and belowground carbon stocks in a Siberian larch watershed

    Science.gov (United States)

    Webb, Elizabeth E.; Heard, Kathryn; Natali, Susan M.; Bunn, Andrew G.; Alexander, Heather D.; Berner, Logan T.; Kholodov, Alexander; Loranty, Michael M.; Schade, John D.; Spektor, Valentin; Zimov, Nikita

    2017-09-01

    (top 10 cm) was positively related to soil moisture and negatively related to moss and lichen cover. These results suggest that, as the climate warms, changes in stand age and structure may be as important as direct climate effects on belowground environmental conditions and permafrost C vulnerability.

  20. Variability in above- and belowground carbon stocks in a Siberian larch watershed

    Directory of Open Access Journals (Sweden)

    E. E. Webb

    2017-09-01

    belowground C storage. Thaw depth was negatively related to stand age, and soil C density (top 10 cm was positively related to soil moisture and negatively related to moss and lichen cover. These results suggest that, as the climate warms, changes in stand age and structure may be as important as direct climate effects on belowground environmental conditions and permafrost C vulnerability.

  1. Effects of Spatial Patch Arrangement and Scale of Covarying Resources on Growth and Intraspecific Competition of a Clonal Plant.

    Science.gov (United States)

    Wang, Yong-Jian; Shi, Xue-Ping; Meng, Xue-Feng; Wu, Xiao-Jing; Luo, Fang-Li; Yu, Fei-Hai

    2016-01-01

    Spatial heterogeneity in two co-variable resources such as light and water availability is common and can affect the growth of clonal plants. Several studies have tested effects of spatial heterogeneity in the supply of a single resource on competitive interactions of plants, but none has examined those of heterogeneous distribution of two co-variable resources. In a greenhouse experiment, we grew one (without intraspecific competition) or nine isolated ramets (with competition) of a rhizomatous herb Iris japonica under a homogeneous environment and four heterogeneous environments differing in patch arrangement (reciprocal and parallel patchiness of light and soil water) and patch scale (large and small patches of light and water). Intraspecific competition significantly decreased the growth of I. japonica, but at the whole container level there were no significant interaction effects of competition by spatial heterogeneity or significant effect of heterogeneity on competitive intensity. Irrespective of competition, the growth of I. japonica in the high and the low water patches did not differ significantly in the homogeneous treatments, but it was significantly larger in the high than in the low water patches in the heterogeneous treatments with large patches. For the heterogeneous treatments with small patches, the growth of I. japonica was significantly larger in the high than in the low water patches in the presence of competition, but such an effect was not significant in the absence of competition. Furthermore, patch arrangement and patch scale significantly affected competitive intensity at the patch level. Therefore, spatial heterogeneity in light and water supply can alter intraspecific competition at the patch level and such effects depend on patch arrangement and patch scale.

  2. The effect of competition on the neutral intraspecific diversity of invasive species.

    Science.gov (United States)

    Roques, L; Hosono, Y; Bonnefon, O; Boivin, T

    2015-08-01

    This paper deals with the effect of interspecific competition on the dynamics of neutral genetic diversity in a range-expanding population. The spread of an invasive species in an environment already hosting a resident competitor is described by a traveling wave solution with minimal speed, u(t,x) = U(x - c ∗ t), of a diffusive Lotka-Volterra competition model. The description of the dynamics of neutral genetic fractions in this wave is based on a decomposition of the wave into several components, as proposed by Roques et al. (Proc Natl Acad Sci USA 109(23):8828-8833, 2012). Our analytical results reveal that the wave can be either the pulled type, corresponding to strong erosion of the diversity, or the pushed type, corresponding to maintenance of the initial diversity. The pulled/pushed nature of the wave depends on the linear or nonlinear nature of the speed c *. Our results show that, for sufficiently strong competition, the speed is nonlinear, and therefore all of the genetic diversity in the invasive population is maintained. Conversely, in the absence of competition, or when competition is mild, the speed is linear, which means that only the furthest forward fraction in the initial invasive population eventually remains in the colonization front. Our numerical results also show that the sufficient conditions of Lewis et al. (J Math Biol 45(3):219-233, 2002) and Huang (J Dyn Differ Equ 22(2):285-297, 2010) for the linearity of the speed c * can still be improved, and they show that nonlinear speeds occur across a wide region of the parameter space, providing a counterpoint to recent analytical results suggesting that nonlinear speeds only occur in certain limiting cases.

  3. A landscape-scale assessment of above- and belowground primary production in coastal wetlands: Implications for climate change-induced community shifts

    Science.gov (United States)

    Stagg, Camille L.; Schoolmaster, Donald R.; Piazza, Sarai C.; Snedden, Gregg; Steyer, Gregory D.; Fischenich, Craig J; McComas, Robert W.

    2017-01-01

    Above- and belowground production in coastal wetlands are important contributors to carbon accumulation and ecosystem sustainability. As sea level rises, we can expect shifts to more salt-tolerant communities, which may alter these ecosystem functions and services. Although the direct influence of salinity on species-level primary production has been documented, we lack an understanding of the landscape-level response of coastal wetlands to increasing salinity. What are the indirect effects of sea-level rise, i.e., how does primary production vary across a landscape gradient of increasing salinity that incorporates changes in wetland type? This is the first study to measure both above- and belowground production in four wetland types that span an entire coastal gradient from fresh to saline wetlands. We hypothesized that increasing salinity would limit rates of primary production, and saline marshes would have lower rates of above- and belowground production than fresher marshes. However, along the Northern Gulf of Mexico Coast in Louisiana, USA, we found that aboveground production was highest in brackish marshes, compared with fresh, intermediate, and saline marshes, and belowground production was similar among all wetland types along the salinity gradient. Multiple regression analysis indicated that salinity was the only significant predictor of production, and its influence was dependent upon wetland type. We concluded that (1) salinity had a negative effect on production within wetland type, and this relationship was strongest in the fresh marsh (0–2 PSU) and (2) along the overall landscape gradient, production was maintained by mechanisms at the scale of wetland type, which were likely related to plant energetics. Regardless of wetland type, we found that belowground production was significantly greater than aboveground production. Additionally, inter-annual variation, associated with severe drought conditions, was observed exclusively for belowground

  4. Effects of Competitive Learning Strategy on Secondary School Students Learning Outcomes: Implications for Counselling

    OpenAIRE

    Chinwe Okereke; Charles N. Ugwuegbulam

    2014-01-01

    This study sought to find out the effects of competitive learning strategy on secondary school students learning outcomes in chemistry. Two null hypotheses were formulated to guide the study. The study adopted a quasi-experimental design. There were 337 senior secondary students II (SSS II) purposively selected from eight (8) intact classes in Imo State from 3 boys only and 3 girls only schools. The instrument for data collection was titled “chemistry Achievement Test” designed by the researc...

  5. The effect of marketing knowledge management on sustainable competitive advantage: Evidence from banking industry

    OpenAIRE

    Fatemeh Rezaee; Mostafa Jafari

    2017-01-01

    Nowadays, the importance of achieving sustainable organization with competitive advantage in complex environments has many researchers’ interest. So, in this study, we evaluate different views of MKM and its role to reach SCA within banking industry. This research is relatively the scarce empirical study and adds to its originality. The findings offer valuable insights on the generalizability of MKM in a research setting. In fact, the purpose of this study is to empirically test the effect of...

  6. Application of electrical capacitance measurement for in situ monitoring of competitive interactions between maize and weed plants

    Directory of Open Access Journals (Sweden)

    Imre Cseresnyés

    2016-06-01

    Full Text Available Applicability of root electrical capacitance (EC measurement for monitoring of crop–weed competition was studied in a pot experiment. Maize (Zea mays L. was grown both alone and with Echinochloa crus-galli or Abutilon theophrasti in different densities with regular measurement of root EC. Plants were harvested 42 days after planting to determine above- and belowground biomass. Depending on weed density, E. crus-galli-A. theophrasti interaction reduced the root EC of maize by 22–66% and 3–57%, respectively. Competitive effect of crop on weeds and intraspecific competition among weeds could also be detected by EC values: E. crus-galli was less sensitive both to the presence of maize and to intraspecific competition than A. theophrasti. Strong linear correlations between root dry mass and root EC for crop and weeds (with R2 from 0.901 to 0.956 were obtained by regression analyses at the end of the experiment. EC monitoring informed us on the emergence time of competition: E. crus-galli interfered with maize root growth a week earlier then A. theophrasti, and increasing weed densities accelerated the emergence of competition. In conclusion, the simple, non-destructive EC method should be considered a potential in situ technique for pot studies on crop–weed competition, which may partially substitute the intrusive techniques commonly used in agricultural researches.

  7. Application of electrical capacitance measurement for in situ monitoring of competitive interactions between maize and weed plants

    Energy Technology Data Exchange (ETDEWEB)

    Cseresnyés, I.; Takács, T.; Füzy, A.; Végh, K.R.; Lehoczky, E.

    2016-11-01

    Applicability of root electrical capacitance (EC) measurement for monitoring of crop–weed competition was studied in a pot experiment. Maize (Zea mays L.) was grown both alone and with Echinochloa crus-galli or Abutilon theophrasti in different densities with regular measurement of root EC. Plants were harvested 42 days after planting to determine above- and belowground biomass. Depending on weed density, E. crus-galli-A. theophrasti interaction reduced the root EC of maize by 22–66% and 3–57%, respectively. Competitive effect of crop on weeds and intraspecific competition among weeds could also be detected by EC values: E. crus-galli was less sensitive both to the presence of maize and to intraspecific competition than A. theophrasti. Strong linear correlations between root dry mass and root EC for crop and weeds (with R2 from 0.901 to 0.956) were obtained by regression analyses at the end of the experiment. EC monitoring informed us on the emergence time of competition: E. crus-galli interfered with maize root growth a week earlier then A. theophrasti, and increasing weed densities accelerated the emergence of competition. In conclusion, the simple, non-destructive EC method should be considered a potential in situ technique for pot studies on crop–weed competition, which may partially substitute the intrusive techniques commonly used in agricultural researches. (Author)

  8. Competitive effects of non-native plants are lowest in native plant communities that are most vulnerable to invasion

    Science.gov (United States)

    J.Stephen Brewer; W. Chase Bailey

    2014-01-01

    Despite widespread acknowledgment that disturbance favors invasion, a hypothesis that has received little attention is whether non-native invaders have greater competitive effects on native plants in undisturbed habitats than in disturbed habitats. This hypothesis derives from the assumption that competitive interactions are more persistent in habitats that have not...

  9. The Response of Old Technology Incumbents to Technological Competition - Does the Sailing Ship Effect Exist?

    DEFF Research Database (Denmark)

    Howells, John

    This article investigates whether firms react to a radical technological substitution threat by a deliberate acceleration of innovation in their existing technology - the 'sailing ship effect'. It has been argued that the effect is both significant and widespread and warrants a reexamination of our...... assumptions about the working of the competitive process (Rosenberg 1972). Reexamination of two cases thought to be exemplars of the effect shows that it existed in neither. It is argued that if the phenomenon occurs, it is likely to be rare...

  10. National Clinical Skills Competition: an effective simulation-based method to improve undergraduate medical education in China

    Directory of Open Access Journals (Sweden)

    Guanchao Jiang

    2016-02-01

    Full Text Available Background: The National Clinical Skills Competition has been held in China for 5 consecutive years since 2010 to promote undergraduate education reform and improve the teaching quality. The effects of the simulation-based competition will be analyzed in this study. Methods: Participation in the competitions and the compilation of the questions used in the competition finals are summarized, and the influence and guidance quality are further analyzed. Through the nationwide distribution of questionnaires in medical colleges, the effects of the simulation-based competition on promoting undergraduate medical education reform were evaluated. Results: The results show that approximately 450 students from more than 110 colleges (accounting for 81% of colleges providing undergraduate clinical medical education in China participated in the competition each year. The knowledge, skills, and attitudes were comprehensively evaluated by simulation-based assessment. Eight hundred and eighty copies of the questionnaires were distributed to 110 participating medical schools in 2015. In total, 752 valid responses were received across 95 schools. The majority of the interviewees agreed or strongly agreed that competition promoted the adoption of advanced educational principles (76.8%, updated the curriculum model and instructional methods (79.8%, strengthened faculty development (84.0%, improved educational resources (82.1%, and benefited all students (53.4%. Conclusions: The National Clinical Skills Competition is widely accepted in China. It has effectively promoted the reform and development of undergraduate medical education in China.

  11. National Clinical Skills Competition: an effective simulation-based method to improve undergraduate medical education in China.

    Science.gov (United States)

    Jiang, Guanchao; Chen, Hong; Wang, Qiming; Chi, Baorong; He, Qingnan; Xiao, Haipeng; Zhou, Qinghuan; Liu, Jing; Wang, Shan

    2016-01-01

    The National Clinical Skills Competition has been held in China for 5 consecutive years since 2010 to promote undergraduate education reform and improve the teaching quality. The effects of the simulation-based competition will be analyzed in this study. Participation in the competitions and the compilation of the questions used in the competition finals are summarized, and the influence and guidance quality are further analyzed. Through the nationwide distribution of questionnaires in medical colleges, the effects of the simulation-based competition on promoting undergraduate medical education reform were evaluated. The results show that approximately 450 students from more than 110 colleges (accounting for 81% of colleges providing undergraduate clinical medical education in China) participated in the competition each year. The knowledge, skills, and attitudes were comprehensively evaluated by simulation-based assessment. Eight hundred and eighty copies of the questionnaires were distributed to 110 participating medical schools in 2015. In total, 752 valid responses were received across 95 schools. The majority of the interviewees agreed or strongly agreed that competition promoted the adoption of advanced educational principles (76.8%), updated the curriculum model and instructional methods (79.8%), strengthened faculty development (84.0%), improved educational resources (82.1%), and benefited all students (53.4%). The National Clinical Skills Competition is widely accepted in China. It has effectively promoted the reform and development of undergraduate medical education in China.

  12. Phenotypic plasticity in Drosophila cactophilic species: the effect of competition, density, and breeding sites.

    Science.gov (United States)

    Fanara, Juan Jose; Werenkraut, Victoria

    2017-08-01

    Changes in the environmental conditions experienced by naturally occurring populations are frequently accompanied by changes in adaptive traits allowing the organism to cope with environmental unpredictability. Phenotypic plasticity is a major aspect of adaptation and it has been involved in population dynamics of interacting species. In this study, phenotypic plasticity (i.e., environmental sensitivity) of morphological adaptive traits were analyzed in the cactophilic species Drosophila buzzatii and Drosophila koepferae (Diptera: Drosophilidae) considering the effect of crowding conditions (low and high density), type of competition (intraspecific and interspecific competition) and cacti hosts (Opuntia and Columnar cacti). All traits (wing length, wing width, thorax length, wing loading and wing aspect) showed significant variation for each environmental factor considered in both Drosophila species. The phenotypic plasticity pattern observed for each trait was different within and between these cactophilic Drosophila species depending on the environmental factor analyzed suggesting that body size-related traits respond almost independently to environmental heterogeneity. The effects of ecological factors analyzed in this study are discussed in order to elucidate the causal factors investigated (type of competition, crowding conditions and alternative host) affecting the election of the breeding site and/or the range of distribution of these cactophilic species. © 2016 Institute of Zoology, Chinese Academy of Sciences.

  13. Effects of subliminal activation of Oedipal fantasies on competitive performance. A replication and extension.

    Science.gov (United States)

    Palumbo, R; Gillman, I

    1984-12-01

    A subliminal psychodynamic activation experiment was conducted in which the effects of five subliminal stimuli were sought on the dart-throwing performance of male subjects. The stimuli consisted of the following messages, each accompanied by a congruent picture: BEATING DAD IS OK, BEATING DAD IS WRONG, BEATING HIM IS OK, BEATING HIM IS WRONG, and PEOPLE ARE WALKING. The first two stimuli were intended to activate competitive motives within the context of the Oedipus complex; the next two, competitive motives outside that context; and the last was intended as a control stimulus. BEATING DAD IS OK led to greater dart-throwing accuracy than each of the other four conditions, which in turn did not differ from each other. This finding replicated a result reported by Silverman, L. H., Ross, D., Adler, J., and Lustig, D. (J. Abnorm. Psychol., 87: 341-357, 1978) and is in keeping with the formulation that the activation of oedipal motives can affect competitive performance. Neither a subject variable (fear of success) nor the differential effects of two experimenters was found to interact with stimulus conditions in affecting dart scores.

  14. Welfare and competition effects of electricity interconnection between Ireland and Great Britain

    International Nuclear Information System (INIS)

    Malaguzzi Valeri, Laura

    2009-01-01

    This study analyzes the effects of additional interconnection on welfare and competition in the Irish electricity market. I simulate the wholesale electricity markets of the island of Ireland and Great Britain for 2005. I find that in order for the two markets to be integrated in 2005, additional interconnection would have to be large. The amount of interconnection decreases for high costs of carbon, since this causes the markets to become more similar. This suggests that in the absence of strategic behavior of firms, most of the gains from trade derive not from differences in size between countries, but from technology differences and are strongly influenced by fuel and carbon costs. Social welfare increases with interconnection, although at a decreasing rate. As the amount of interconnection increases, there are also positive effects on competition in Ireland, the less competitive of the two markets. Finally, it is unlikely that private investors will pay for the optimal amount of interconnection since their returns are significantly smaller than the total social benefit of interconnection. (author)

  15. The effect of temperature on growth and competition between Sphagnum species.

    Science.gov (United States)

    Breeuwer, Angela; Heijmans, Monique M P D; Robroek, Bjorn J M; Berendse, Frank

    2008-05-01

    Peat bogs play a large role in the global sequestration of C, and are often dominated by different Sphagnum species. Therefore, it is crucial to understand how Sphagnum vegetation in peat bogs will respond to global warming. We performed a greenhouse experiment to study the effect of four temperature treatments (11.2, 14.7, 18.0 and 21.4 degrees C) on the growth of four Sphagnum species: S. fuscum and S. balticum from a site in northern Sweden and S. magellanicum and S. cuspidatum from a site in southern Sweden. In addition, three combinations of these species were made to study the effect of temperature on competition. We found that all species increased their height increment and biomass production with an increase in temperature, while bulk densities were lower at higher temperatures. The hollow species S. cuspidatum was the least responsive species, whereas the hummock species S. fuscum increased biomass production 13-fold from the lowest to the highest temperature treatment in monocultures. Nutrient concentrations were higher at higher temperatures, especially N concentrations of S. fuscum and S. balticum increased compared to field values. Competition between S. cuspidatum and S. magellanicum was not influenced by temperature. The mixtures of S. balticum with S. fuscum and S. balticum with S. magellanicum showed that S. balticum was the stronger competitor, but it lost competitive advantage in the highest temperature treatment. These findings suggest that species abundances will shift in response to global warming, particularly at northern sites where hollow species will lose competitive strength relative to hummock species and southern species.

  16. Effects of Increased Competition on Quality of Primary Care in Sweden

    DEFF Research Database (Denmark)

    Dietrichson, Jens; Ellegård, Lina Maria; Kjellsson, Gustav

    quality is scarce, in particular regarding primary care. This paper adds evidence from recent reforms of Swedish primary care that affected competition in municipal markets differently depending on the pre- reform market structure. Using a difference-in-differences strategy, we demonstrate...... that the reforms led to substantially more entry of private care providers in municipalities where there were many patients per provider before the reforms. The effects on primary care quality in these municipalities are modest: we find small improvements in subjective measures of overall care quality......, but no significant effects on the rate of avoidable hospitalizations or patients’ satisfaction with access to care. We find no indications of quality reductions....

  17. Increased stem density and competition may diminish the positive effects of warming at alpine treeline.

    Science.gov (United States)

    Wang, Yafeng; Pederson, Neil; Ellison, Aaron M; Buckley, Hannah L; Case, Bradley S; Liang, Eryuan; Julio Camarero, J

    2016-07-01

    The most widespread response to global warming among alpine treeline ecotones is not an upward shift, but an increase in tree density. However, the impact of increasing density on interactions among trees at treeline is not well understood. Here, we test if treeline densification induced by climatic warming leads to increasing intraspecific competition. We mapped and measured the size and age of Smith fir trees growing in two treelines located in the southeastern Tibetan Plateau. We used spatial point-pattern and codispersion analyses to describe the spatial association and covariation among seedlings, juveniles, and adults grouped in 30-yr age classes from the 1860s to the present. Effects of competition on tree height and regeneration were inferred from bivariate mark-correlations. Since the 1950s, a rapid densification occurred at both sites in response to climatic warming. Competition between adults and juveniles or seedlings at small scales intensified as density increased. Encroachment negatively affected height growth and further reduced recruitment around mature trees. We infer that tree recruitment at the studied treelines was more cold-limited prior to 1950 and shifted to a less temperature-constrained regime in response to climatic warming. Therefore, the ongoing densification and encroachment of alpine treelines could alter the way climate drives their transitions toward subalpine forests. © 2016 by the Ecological Society of America.

  18. Effects of Noise on Ecological Invasion Processes: Bacteriophage-Mediated Competition in Bacteria

    Science.gov (United States)

    Joo, Jaewook; Harvill, Eric; Albert, Réka

    2007-07-01

    Pathogen-mediated competition, through which an invasive species carrying and transmitting a pathogen can be a superior competitor to a more vulnerable resident species, is one of the principle driving forces influencing biodiversity in nature. Using an experimental system of bacteriophage-mediated competition in bacterial populations and a deterministic model, we have shown in Joo et al. [ Proc. R. Soc. B 273,1843-1848 (2006)] that the competitive advantage conferred by the phage depends only on the relative phage pathology and is independent of the initial phage concentration and other phage and host parameters such as the infection-causing contact rate, the spontaneous and infection-induced lysis rates, and the phage burst size. Here we investigate the effects of stochastic fluctuations on bacterial invasion facilitated by bacteriophage, and examine the validity of the deterministic approach. We use both numerical and analytical methods of stochastic processes to identify the source of noise and assess its magnitude. We show that the conclusions obtained from the deterministic model are robust against stochastic fluctuations, yet deviations become prominently large when the phage are more pathological to the invading bacterial strain.

  19. Competitive and Cooperative Effects during Nickel Adsorption to Iron Oxides in the Presence of Oxalate

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Elaine D. [Department of Earth and Planetary; Catalano, Jeffrey G. [Department of Earth and Planetary

    2017-08-09

    Iron oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals via adsorption and coprecipitation. The presence of organic acids may potentially alter how metals associate with iron oxide minerals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, and surface site competition. The macroscopic and molecular-scale effects of these processes were investigated for Ni adsorption to hematite and goethite at pH 7 in the presence of oxalate. The addition of this organic acid suppresses Ni uptake on both minerals. Aqueous speciation suggests that this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni2+ in solution suggests that the oxalate also alters Ni adsorption affinity. EXAFS and ATR-FTIR spectroscopies indicate that these changes in binding affinity are due to the formation of Ni–oxalate ternary surface complexes. These observations demonstrate that competition between dissolved oxalate and the mineral surface for Ni overwhelms the enhancement in adsorption associated with ternary complexation. Oxalate thus largely enhances Ni mobility, thereby increasing micronutrient bioavailability and inhibiting contaminant sequestration.

  20. Effects of Noise on Ecological Invasion Processes: Bacteriophage-mediated Competition in Bacteria

    Science.gov (United States)

    Joo, Jaewook; Eric, Harvill; Albert, Reka

    2007-03-01

    Pathogen-mediated competition, through which an invasive species carrying and transmitting a pathogen can be a superior competitor to a more vulnerable resident species, is one of the principle driving forces influencing biodiversity in nature. Using an experimental system of bacteriophage-mediated competition in bacterial populations and a deterministic model, we have shown in [Joo et al 2005] that the competitive advantage conferred by the phage depends only on the relative phage pathology and is independent of the initial phage concentration and other phage and host parameters such as the infection-causing contact rate, the spontaneous and infection-induced lysis rates, and the phage burst size. Here we investigate the effects of stochastic fluctuations on bacterial invasion facilitated by bacteriophage, and examine the validity of the deterministic approach. We use both numerical and analytical methods of stochastic processes to identify the source of noise and assess its magnitude. We show that the conclusions obtained from the deterministic model are robust against stochastic fluctuations, yet deviations become prominently large when the phage are more pathological to the invading bacterial strain.

  1. Acute effect of different stretching methods on flexibility and jumping performance in competitive artistic gymnasts.

    Science.gov (United States)

    Dallas, G; Smirniotou, A; Tsiganos, G; Tsopani, D; Di Cagno, A; Tsolakis, Ch

    2014-12-01

    The purpose of this study was to investigate the acute effects of 3 different warm up methods of stretching (static, proprioceptive neuromuscular facilitation, and stretching exercises on a Vibration platform) on flexibility and legs power-jumping performance in competitive artistic gymnasts. Eighteen competitive artistic gymnasts were recruited to participate in this study. Subjects were exposed to each of 3 experimental stretching conditions: static stretching (SS), proprioceptive neuromuscular facilitation stretching (PNF), and stretching exercises on a Vibration platform (S+V). Flexibility assessed with sit and reach test (S & R) and jumping performance with squat jump (SJ) and counter movement jump (CMJ) and were measured before, immediately after and 15 min after the interventions. Significant differences were observed for flexibility after all stretching conditions for S+V (+1.1%), SS (+5.7%) and PNF (+6.8%) (P=0.000), which remained higher 15 min after interventions (S+V (1.1%), SS (5.3%) and PNF (5.5%), respectively (P=0.000). PNF stretching increased flexibility in competitive gymnasts, while S+V maintained jumping performance when both methods were used as part of a warm-up procedure.

  2. Weed Competition and its Effects on Pwani Hybrid 1 Maize Grain Yields in Coastal Kenya

    International Nuclear Information System (INIS)

    Kamau, G.M.; Saha, H.M.

    1999-01-01

    Weed competition is a serious constraint to maize production in coastal Kenya. A trial to asses the effects of weed competition on performance of maize was planted at Regional Research Centre-Mtwapa and Msabaha Research Sub-centre-Malindi in 1992. Pwani hybrid 1 maize was used in the trials. Weeding was done at weekly intervals from germination up to the sixth week in an additive weed removal system and plots maintained weed free afterwards. A weedy and a weed free plot were used as checks. Data on plant counts plant heights, weed biomass, weed identification and maize grain yield at 15 % MC were all recorded. There was a significant difference between weed and weedy free plots for grain yield, plant height and weed biomass for both sites. A 53% maize grain yield reduction due to weed competition was recorded. A 3% grain yield reduction equivalent to 1.03 bags for every week's delay in weeding after the first to weeks was realised for both sites. There was a corresponding grain yield loss as delay in weeding increased

  3. Effect of larval crowding on mating competitiveness of Anopheles gambiae mosquitoes

    Directory of Open Access Journals (Sweden)

    Knols Bart GJ

    2005-09-01

    Full Text Available Abstract Background The success of sterile or transgenic Anopheles for malaria control depends on their mating competitiveness within wild populations. Current evidence suggests that transgenic mosquitoes have reduced fitness. One means of compensating for this fitness deficit would be to identify environmental conditions that increase their mating competitiveness, and incorporate them into laboratory rearing regimes. Methods Anopheles gambiae larvae were allocated to three crowding treatments with the same food input per larva. Emerged males were competed against one another for access to females, and their corresponding longevity and energetic reserves measured. Results Males from the low-crowding treatment were much more likely to acquire the first mating. They won the first female approximately 11 times more often than those from the high-crowding treatment (Odds ratio = 11.17 and four times more often than those from the medium-crowding treatment (Odds ratio = 3.51. However, there was no overall difference in the total number of matings acquired by males from different treatments (p = 0.08. The survival of males from the low crowding treatment was lower than those from other treatments. The body size and teneral reserves of adult males did not differ between crowding treatments, but larger males were more likely to acquire mates than small individuals. Conclusion Larval crowding and body size have strong, independent effects on the mating competitiveness of adult male An. gambiae. Thus manipulation of larval crowding during mass rearing could provide a simple technique for boosting the competitiveness of sterile or transgenic male mosquitoes prior to release.

  4. Effects of an accelerated liberalization. Consequences of accelerated liberalization for the competitiveness of Dutch energy companies

    International Nuclear Information System (INIS)

    Kaal, M.B.T.

    2001-08-01

    One of the conclusions of the Dutch Energy Report, published at the end of 1999, was that it would be feasible to speed up the pace of liberalization in the Netherlands. This conclusion will lead to the liberalization of the retail customers in 2004 and the market for renewable energy in 2001. This will be an incentive to more competition and put a greater pressure on energy companies to concentrate in order to benefit from economies of scale. Less preparation time implies also that there will be less layers of isolation against cost leaders and hence a more intense (price-based) competition. The central question in this report is whether and to what extent the effects of policy, in particular the accelerated liberalization, affect the strategic behavior and competitiveness of the Dutch Regional Electricity Companies (RECs). To address this question four face-to-face interviews have been held with experts from the four major RECs. In these interviews the experts gave their opinion about the Dutch policy regarding the accelerated liberalization and the rate and extent of the privatization. Subsequently, their perspective on the impact of the policy on their competitiveness and their analysis of the Dutch energy market was recorded. After that, the experts exposed their outlook on the future energy market and the ambition and most likely direction of their companies. The data collection was complemented with numerous relevant public interviews of experts derived from various newspapers and energy magazines. The data thus collected were analyzed by means of a theoretical framework consisting of the insights of Porter, Prahalad and Hamel and at a more detailed level marketing theories regarding positioning and branding. This resulted in an overview of the current market position of the Dutch RECs and an outlook for the years to come. 27 refs

  5. Interspecific competition counteracts negative effects of dispersal on adaptation of an arthropod herbivore to a new host.

    Science.gov (United States)

    Alzate, A; Bisschop, K; Etienne, R S; Bonte, D

    2017-11-01

    Dispersal and competition have both been suggested to drive variation in adaptability to a new environment, either positively or negatively. A simultaneous experimental test of both mechanisms is however lacking. Here, we experimentally investigate how population dynamics and local adaptation to a new host plant in a model species, the two-spotted spider mite (Tetranychus urticae), are affected by dispersal from a stock population (no-adapted) and competition with an already adapted spider mite species (Tetranychus evansi). For the population dynamics, we find that competition generally reduces population size and increases the risk of population extinction. However, these negative effects are counteracted by dispersal. For local adaptation, the roles of competition and dispersal are reversed. Without competition, dispersal exerts a negative effect on adaptation (measured as fecundity) to a novel host and females receiving the highest number of immigrants performed similarly to the stock population females. By contrast, with competition, adding more immigrants did not result in a lower fecundity. Females from populations with competition receiving the highest number of immigrants had a significantly higher fecundity than females from populations without competition (same dispersal treatment) and than the stock population females. We suggest that by exerting a stronger selection on the adapting populations, competition can counteract the migration load effect of dispersal. Interestingly, adaptation to the new host does not significantly reduce performance on the ancestral host, regardless of dispersal rate or competition. Our results highlight that assessments of how species can adapt to changing conditions need to jointly consider connectivity and the community context. © 2017 The Authors. Journal of Evolutionary Biology Published by John Wiley & Sons ltd on Behalf of European Society for Evolutionary Biology.

  6. Contribution of above- and below-ground plant traits to the structure and function of grassland soil microbial communities.

    Science.gov (United States)

    Legay, N; Baxendale, C; Grigulis, K; Krainer, U; Kastl, E; Schloter, M; Bardgett, R D; Arnoldi, C; Bahn, M; Dumont, M; Poly, F; Pommier, T; Clément, J C; Lavorel, S

    2014-10-01

    Abiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover. In mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities. Direct effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification. The results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. From sublexical facilitation to lexical competition: ERP effects of masked neighbor priming.

    Science.gov (United States)

    Meade, Gabriela; Grainger, Jonathan; Midgley, Katherine J; Emmorey, Karen; Holcomb, Phillip J

    2018-04-15

    Interactive-activation models posit that visual word recognition involves co-activation of orthographic neighbors (e.g., note, node) and competition among them via lateral inhibitory connections. Behavioral evidence of this lexical competition comes from masked priming paradigms, in which target words elicit slower responses when preceded by a neighbor (e.g., note-NODE) than when preceded by an unrelated word (e.g., kiss-NODE). In the present study, we used ERPs to investigate how masked high frequency word primes influence processing of low frequency word and pseudoword targets. Word targets preceded by a neighbor prime elicited larger negativities within the N400 window than those preceded by an unrelated prime across bilateral anterior sites, which we call a reversed N400 priming effect. Consistent with the behavioral literature, the size of the reversed N400 priming effect was larger for targets from high-density orthographic neighborhoods and for participants who scored higher on a behavioral measure of spelling recognition. Indeed, the opposite effect (i.e., smaller negativities within the N400 window for word targets preceded by a neighbor) was observed for words from low-density orthographic neighborhoods and for less-skilled spellers. Traditional priming was also observed within the N250 window for word targets and within both the N250 or N400 windows for pseudoword targets. The specificity of the reversed N400 priming effect to situations in which both words have precise lexical representations suggests that it, like the behavioral interference effect, indexes lexical competition during visual word recognition. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Consumer interaction strength may limit the diversifying effect of intraspecific competition: a test in alewife (Alosa pseudoharengus).

    Science.gov (United States)

    Jones, Andrew W; Post, David M

    2013-06-01

    Intraspecific competition is considered a principal driver of dietary variation, but empirical studies provide mixed support for this mechanism. Here we link comparative and experimental work testing the effects of competition and resource availability on the dietary variation of the alewife (Alosa pseudoharengus). The alewife, a consumer with extreme effects on its resources, was specifically utilized to additionally test the idea that strong interactions between a consumer and its resources can diminish the diversifying effect of competition. First, we compared the short- and long-term diet measures of wild populations across a wide range of densities. Second, in a pair of large-scale field mesocosm experiments, we explored the influence of competition and interaction strength on alewife dietary variation. Results from a whole-lake comparison and field experiments indicated that increasing competition was negatively correlated with population dietary variation. Further, altering the strength of the interaction between the alewife and its prey via prey supplementation eliminated this negative relationship. Collectively, our results suggest that competitive interactions may not drive dietary diversification in the alewife and, potentially, in other highly effective consumers. Our results also indicate that further consideration of the strength of species interactions (and the consumer traits that underlie them) would improve our understanding of the link between intraspecific competition and variation.

  9. Sedimentation and belowground carbon accumulation rates in mangrove forests that differ in diversity and land use: a tale of two mangroves

    Science.gov (United States)

    Richard A. MacKenzie; Patra B. Foulk; J. Val Klump; Kimberly Weckerly; Joko Purbospito; Daniel Murdiyarso; Daniel C. Donato; Vien Ngoc Nam

    2016-01-01

    Increased sea level is the climate change effect expected to have the greatest impact on mangrove forest survival. Mangroves have survived extreme fluctuations in sea level in the past through sedimentation and belowground carbon (C) accumulation, yet it is unclear what factors may influence these two parameters. We measured sedimentation, vertical accretion, and...

  10. Effect of Economic Vulnerability on Competitive Advantages, Enterprise Performance and Sustainability

    Directory of Open Access Journals (Sweden)

    Abdullah Al Mamun

    2018-04-01

    Full Text Available This study investigated the effect of economic vulnerability upon competitive advantages, performance, and sustainability of micro-enterprises owned and managed by micro-entrepreneurs who participate in varied development initiatives in Peninsular Malaysia. Upon adopting the cross-sectional design, data were randomly collected from selected 300 micro-entrepreneurs from the eKasih program (national poverty data bank located in four states of Peninsular Malaysia. The quantitative data were collected by conducting structured interview sessions with the respondents held from September until November 2017. The findings revealed that the state of economic vulnerability among the respondents had a significantly negative effect on the aspects of competitive advantages, performance, and sustainability among micro-enterprises in Peninsular Malaysia. Despite of the widely acknowledged and empirically examined effects of socioeconomic antecedents upon micro-enterprise performance, the focus on the effect of a more comprehensive measure of socioeconomic condition, that is, economic vulnerability, among low-income households appears to be scant. Hence, the outcomes of this study are able to provide critical insights for development organizations pertaining to development programs and their effectiveness on economically vulnerable, particularly among low-income households in Peninsular Malaysia.

  11. Oncogenic Nras has bimodal effects on stem cells that sustainably increase competitiveness.

    Science.gov (United States)

    Li, Qing; Bohin, Natacha; Wen, Tiffany; Ng, Victor; Magee, Jeffrey; Chen, Shann-Ching; Shannon, Kevin; Morrison, Sean J

    2013-12-05

    'Pre-leukaemic' mutations are thought to promote clonal expansion of haematopoietic stem cells (HSCs) by increasing self-renewal and competitiveness; however, mutations that increase HSC proliferation tend to reduce competitiveness and self-renewal potential, raising the question of how a mutant HSC can sustainably outcompete wild-type HSCs. Activating mutations in NRAS are prevalent in human myeloproliferative neoplasms and leukaemia. Here we show that a single allele of oncogenic Nras(G12D) increases HSC proliferation but also increases reconstituting and self-renewal potential upon serial transplantation in irradiated mice, all prior to leukaemia initiation. Nras(G12D) also confers long-term self-renewal potential to multipotent progenitors. To explore the mechanism by which Nras(G12D) promotes HSC proliferation and self-renewal, we assessed cell-cycle kinetics using H2B-GFP label retention and 5-bromodeoxyuridine (BrdU) incorporation. Nras(G12D) had a bimodal effect on HSCs, increasing the frequency with which some HSCs divide and reducing the frequency with which others divide. This mirrored bimodal effects on reconstituting potential, as rarely dividing Nras(G12D) HSCs outcompeted wild-type HSCs, whereas frequently dividing Nras(G12D) HSCs did not. Nras(G12D) caused these effects by promoting STAT5 signalling, inducing different transcriptional responses in different subsets of HSCs. One signal can therefore increase HSC proliferation, competitiveness and self-renewal through bimodal effects on HSC gene expression, cycling and reconstituting potential.

  12. Effects of Hypoxic Training versus Normoxic Training on Exercise Performance in Competitive Swimmers.

    Science.gov (United States)

    Park, Hun-Young; Lim, Kiwon

    2017-12-01

    In swimming competition, optimal swimming performance is characterized by a variety of interchangeable components, such as aerobic exercise capacity, anaerobic power and muscular function. Various hypoxic training methods would potentiate greater performance improvements compared to similar training at sea-level. Therefore, this study aimed to evaluate the effects of six-weeks of hypoxic training on exercise performance in moderately trained competitive swimmers. Twenty swimmers were equally divided into a normoxic training group (n = 10) for residing and training at sea-level (P I O 2 = 149.7 mmHg), and a hypoxic training group (n = 10) for residing at sea-level but training at 526 mmHg hypobaric hypoxic condition (P I O 2 = 100.6 mmHg). Aerobic exercise capacity, anaerobic power, muscular function, hormonal response and 50 and 400 m swimming performance were measured before and after training, which was composed of warm-up, continuous training, interval training, elastic resistance training, and cool-down. The training frequency was 120 min, 3 days per week for 6 weeks. Muscular function and hormonal response parameters showed significant interaction effects (all p 0.288) in muscular strength and endurance, growth hormone; GH, insulin like growth factor-1; IGF-1, and vascular endothelial growth factor; VEGF. The other variables demonstrated no significant interaction effects. However, a hypoxic training group also showed significantly increased maximal oxygen consumption; VO 2 max (p = 0.001), peak anaerobic power (p = 0.001), and swimming performances for 50 m (p = 0.000) and 400 m (p = 0.000). These results indicated that the hypoxic training method proposed in our study is effective for improvement of muscular strength and endurance in moderately trained competitive swimmers compared to control group. However, our hypoxic training method resulted in unclear changes in aerobic exercise capacity (VO 2 max), anaerobic power, and swimming performance of 50 m and

  13. Effects of Hypoxic Training versus Normoxic Training on Exercise Performance in Competitive Swimmers

    Directory of Open Access Journals (Sweden)

    Hun-Young Park, Kiwon Lim

    2017-12-01

    Full Text Available In swimming competition, optimal swimming performance is characterized by a variety of interchangeable components, such as aerobic exercise capacity, anaerobic power and muscular function. Various hypoxic training methods would potentiate greater performance improvements compared to similar training at sea-level. Therefore, this study aimed to evaluate the effects of six-weeks of hypoxic training on exercise performance in moderately trained competitive swimmers. Twenty swimmers were equally divided into a normoxic training group (n = 10 for residing and training at sea-level (PIO2 = 149.7 mmHg, and a hypoxic training group (n = 10 for residing at sea-level but training at 526 mmHg hypobaric hypoxic condition (PIO2 = 100.6 mmHg. Aerobic exercise capacity, anaerobic power, muscular function, hormonal response and 50 and 400 m swimming performance were measured before and after training, which was composed of warm-up, continuous training, interval training, elastic resistance training, and cool-down. The training frequency was 120 min, 3 days per week for 6 weeks. Muscular function and hormonal response parameters showed significant interaction effects (all p 0.288 in muscular strength and endurance, growth hormone; GH, insulin like growth factor-1; IGF-1, and vascular endothelial growth factor; VEGF. The other variables demonstrated no significant interaction effects. However, a hypoxic training group also showed significantly increased maximal oxygen consumption; VO2max (p = 0.001, peak anaerobic power (p = 0.001, and swimming performances for 50 m (p = 0.000 and 400 m (p = 0.000. These results indicated that the hypoxic training method proposed in our study is effective for improvement of muscular strength and endurance in moderately trained competitive swimmers compared to control group. However, our hypoxic training method resulted in unclear changes in aerobic exercise capacity (VO2max, anaerobic power, and swimming performance of 50 m and

  14. The effect of badminton-specific exercise on badminton short-serve performance in competition and practice climates.

    Science.gov (United States)

    Duncan, Michael J; Chan, Cheryl K Y; Clarke, Neil D; Cox, Martin; Smith, Mike

    2017-03-01

    This study examined the effects of changes in physiological and psychological arousal on badminton short-serve performance in competitive and practice climates. Twenty competitive badminton players (10 males and 10 females) volunteered to participate in the study following ethics approval. After familiarisation, badminton short-serve performance was measured at rest, mid-way through and at the end of a badminton-specific exercise protocol in two conditions; competition vs. practice. Ratings of cognitive and somatic anxiety were assessed at three time points prior to badminton short-serve performance using the Mental Readiness Form 3. Heart rate and rating of perceived exertion (RPE) were assessed during the exercise protocol. Results indicated that better short-serve performance was evident in practice compared to competition (P = .034). RPE values were significantly higher in the competition condition compared to practice (P = .007). Cognitive anxiety intensity was significantly lower post-exercise in the practice condition compared to competition (P = .001). Cognitive anxiety direction showed greater debilitation post-exercise in the competition condition compared to practice (P = .01). Somatic anxiety intensity increased from pre-, to mid- to post-exercise (P = .001) irrespective of condition. This study suggests that badminton serve performance is negatively affected when physiological arousal, via badminton-specific exercise, and cognitive anxiety, via perceived competition, are high.

  15. EDITORIAL: Physics competitions Physics competitions

    Science.gov (United States)

    Jordens, H.; Mathelitsch, L.

    2009-11-01

    students are allowed to use any method they like, are coached by teachers, and are encouraged to ask for help from experts at research centres or universities. Finally, they must prepare a 12-minute presentation. A tournament consists of different contests. In each contest, three teams are involved: the reporting team is challenged by an opponent team to present a task. This presentation is then criticized by the opponent, pointing out merits and possible weak parts. The discussion between the two representatives of the teams is a central element of a contest. The third team acts as reviewer, giving final comments on the performances of the contesting teams. At the end, a jury grades the performances of all three teams. Then, the different roles of the teams rotate, and the students also rotate roles within the teams. The competition started in the former Soviet Union in 1988 and became international for the first time in 1994 when it was organized in Groningen, The Netherlands. In the 2008 tournament in Trogir, Croatia, teams from 24 countries participated [5]. Since this tournament is younger and less known, the national pre-selections are not as well established and numerous as for the Olympiad. Also, the training is different: in addition to developing experimental skills and physical understanding of the problems, the students must organize their performances, share work and responsibilities, and must train in the techniques of presentation and debate (in English). The winner of the tournament in Croatia was the team from Germany. Their presentation in the finals was an experimental and theoretical investigation into the Kaye effect. The students wrote up their presentation, and it is reproduced here as the second paper in this special section. Again, different in spirit and aim is 'First Step to Nobel Prize in Physics' [6]. This competition started in 1991 in Poland and encourages students to take their first steps in physics research. Students of 20 years old or

  16. The Effects of Resistance Training on Golf Performance and Physiological Stress Response During Competition in Intercollegiate Golfers

    National Research Council Canada - National Science Library

    Doan, Brandon

    2002-01-01

    ...) on clubhead speed, consistency, and putting distance control. 2) To investigate the effects of 36 continuous holes of competitive golf on testosterone and cortisol response and their relation to performance. Study #1...

  17. Measuring competitiveness

    OpenAIRE

    J. Peter Neary

    2005-01-01

    An earlier version was presented at the Conference on Macroeconomic Perspectives in Honour of Brendan M. Walsh, held at University College Dublin on 7 October, 2005 This paper reviews alternative approaches to measuring an economy?s cost competitiveness and proposes some new measures inspired by the economic theory of index numbers. The indices provide a theoretical benchmark for estimated real effective exchange rates, but differ from standard measures in that they are based on marginal r...

  18. Electricity supply. The effects of competitive power purchases are not yet certain

    International Nuclear Information System (INIS)

    England-Joseph, Judy; Wood, David G.; Bausell, Charles W. Jr.; Farah, Philip G.; Alexander, Alice M.; Griffes, Peter H.; Jorritsma, James S.; Skud, Bruce; Dunbrack, Linda W.

    1990-08-01

    Most electricity in the United States is produced by utilities that own and operate facilities for the generation, transmission, and distribution of power. Utilities traditionally have operated as regulated monopolists, each within an established geographic area. In return, utilities have an obligation to provide reliable electricity to all consumers in their territory at a reasonable price. Many utility companies also participate in power pools, under which they may purchase electricity from one another to meet requirements. Utilities are allowed to earn a return on plants they own and operate, while the costs of purchased electricity are passed directly to consumers. To encourage the development of alternative energy resources, the Public Utility Regulatory Policies Act of 1978, as amended, (PURPA) required utilities to purchase power offered by qualifying facilities at a price not exceeding the utilities' avoided cost of generating it or purchasing it from another source. In part to help state regulators and utilities determine utilities' avoided costs and to help sort through a flood of bids, competitive bidding, which allows market forces to help determine prices, has emerged as a means of purchasing power from nonutility generators. Because several years are often required to construct generating sources, utilities have little operating experience with competitively purchased electricity. Thus, the effects of competitive power purchases on the long-term reliability of electric service - which is affected by the reliability of all sources and transmission and distribution facilities are not yet certain and difficult to assess. Among the three utilities reviewed, only at Central Maine Power have sources of competitively purchased power entered service, and they have operated reliably. However, each utility reviewed has accepted bids that were subsequently withdrawn, for financial or other reasons, prior to scheduled service dates. When selecting nonutility

  19. [Perceptual conflict and response competition: event-related potentials of the stroop effect].

    Science.gov (United States)

    Bekçi, Belma; Karakaş, Sirel

    2009-01-01

    The aim of the present study was to analyze electrophysiological activity associated with the Stroop effect. The sample included 50 healthy volunteer adults (23 female and 27 male) from the university population. Stimulation, recording and analyses were carried under NeuroScan 4.2 hardware-software system. The effect of the experimental variables (stimulus congruency, response accuracy and electrode location) on event-related potentials (ERPs) was studied using 2x2x3 analysis of variance for repeated measures. The Stroop effect was demonstrated as prolonged reaction time to incongruent stimuli and increased total number of missed stimuli. Principal components analysis (PCA) showed that Stroop performance was related such factors as selective attention, interference, and resistance to interference. The electrophysiological Stroop effect was demonstrated as increased amplitude of P3 and N4 peaks for incongruent stimuli, and of N2, P3, N3, and N4 peaks for incorrect responses. Increased amplitude of P3 and N4 peaks associated with stimulus-related activation has been suggested to reflect conflict detection process. The variations in amplitudes for incorrect responses were complicated. While the amplitude of the N2 and P3 components increased only for incongruent stimuli, those of the N3 and N4 components increased for both congruent and incongruent stimuli. It was concluded that these earlier and later activations were associated with response competition and error detection processes, respectively. In this respect, these findings support both the perceptual conflict and the response competition hypotheses of Stroop interference.

  20. Competition between deferiprone, desferrioxamine and other chelators for iron and the effect of other metals.

    Science.gov (United States)

    Sheppard, L N; Kontoghiorghes, G J

    1993-06-01

    Competition for iron between the leading oral iron chelator deferiprone (L1, 1,2-dimethyl-3-hydroxypyrid-4-one) and desferrioxamine (DF), and the effect of other metals has been studied. Visible spectroscopy was used to estimate the displacement of iron from DF-iron(III) and L1-iron(III) complexes, respectively, by varying quantities of up to 100 molar equivalent of a competing metal ion M+ (Mg2+, Al3+, Ca2+, Mn2+, Co2+, Cu2+, Zn2+ and Pb2+) at physiological pH. Copper and aluminium showed the greatest competition against iron, while magnesium, calcium and manganese had little or no effect and the other metals an intermediate effect. DF showed greater selectivity for iron than L1 under these conditions. An analogous series of experiments carried out using a competing chelator of up to 50 molar equivalent in a place of a competing metal ion showed that 8-hydroxyquinoline, diethylenetriamine-pentaacetic acid (DTPA) and tropolone were more effective at displacing iron from DF-Fe and (L1)3Fe complexes than maltol or omadine. Desferrioxamine was the most efficient competitor against L1. Stoichiometric studies of the L1 complexes of aluminium and copper at pH 7.4 using Job Plots, suggested the formation of (L1)3Al and (L1)2Cu complexes, respectively.

  1. Seasonal variations of belowground carbon transfer assessed by in situ 13CO2 pulse labelling of trees

    Directory of Open Access Journals (Sweden)

    L. Barthes

    2011-05-01

    Full Text Available Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objective of our study was to assess patterns of belowground carbon allocation among tree species and along seasons. Pure 13CO2 pulse labelling of the entire crown of three different tree species (beech, oak and pine was carried out at distinct phenological stages. Excess 13C in soil CO2 efflux was tracked using tuneable diode laser absorption spectrometry to determine time lags between the start of the labelling and the appearance of 13C in soil CO2 efflux and the amount of 13C allocated to soil CO2 efflux. Isotope composition (δ13C of CO2 respired by fine roots and soil microbes was measured at several occasions after labelling, together with δ13C of bulk root tissue and microbial carbon. Time lags ranged from 0.5 to 1.3 days in beech and oak and were longer in pine (1.6–2.7 days during the active growing season, more than 4 days during the resting season, and the transfer of C to the microbial biomass was as fast as to the fine roots. The amount of 13C allocated to soil CO2 efflux was estimated from a compartment model. It varied between 1 and 21 % of the amount of 13CO2 taken up by the crown, depending on the species and the season. While rainfall exclusion that moderately decreased soil water content did not affect the pattern of carbon allocation to soil CO2 efflux in beech, seasonal patterns of carbon allocation belowground differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with the strength of other sinks (aboveground growth in late spring and storage in late summer that were not observed in oak. We report a fast transfer of recent photosynthates to the mycorhizosphere and we conclude that the

  2. Seasonal variations of belowground carbon transfer assessed by in situ 13CO2 pulse labelling of trees

    Science.gov (United States)

    Epron, D.; Ngao, J.; Dannoura, M.; Bakker, M. R.; Zeller, B.; Bazot, S.; Bosc, A.; Plain, C.; Lata, J. C.; Priault, P.; Barthes, L.; Loustau, D.

    2011-05-01

    Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objective of our study was to assess patterns of belowground carbon allocation among tree species and along seasons. Pure 13CO2 pulse labelling of the entire crown of three different tree species (beech, oak and pine) was carried out at distinct phenological stages. Excess 13C in soil CO2 efflux was tracked using tuneable diode laser absorption spectrometry to determine time lags between the start of the labelling and the appearance of 13C in soil CO2 efflux and the amount of 13C allocated to soil CO2 efflux. Isotope composition (δ13C) of CO2 respired by fine roots and soil microbes was measured at several occasions after labelling, together with δ13C of bulk root tissue and microbial carbon. Time lags ranged from 0.5 to 1.3 days in beech and oak and were longer in pine (1.6-2.7 days during the active growing season, more than 4 days during the resting season), and the transfer of C to the microbial biomass was as fast as to the fine roots. The amount of 13C allocated to soil CO2 efflux was estimated from a compartment model. It varied between 1 and 21 % of the amount of 13CO2 taken up by the crown, depending on the species and the season. While rainfall exclusion that moderately decreased soil water content did not affect the pattern of carbon allocation to soil CO2 efflux in beech, seasonal patterns of carbon allocation belowground differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with the strength of other sinks (aboveground growth in late spring and storage in late summer) that were not observed in oak. We report a fast transfer of recent photosynthates to the mycorhizosphere and we conclude that the patterns of carbon

  3. Effects of shading on relative competitive advantage of three species of Sphagnum

    Directory of Open Access Journals (Sweden)

    J.Z. Ma

    2015-06-01

    Full Text Available (1 Sphagnum is an important genus of bryophytes holding 10–15 % of the terrestrial carbon stock. With climate change a drier surface may increase the abundance of vascular plants on peatlands, so shading of Sphagnum may increase. Here we describe growth cabinet experiments to reveal the effects of shading on interactions among mixtures of three species: S. capillifolium, S. palustre (hummock species, and S. fallax (a hollow species. We measured the six traits: growth in length, growth as increase in dry mass, side-shoot production, nitrogen and carbon proportion of the capitulum dry mass, and C:N ratio in the capitulum. (2 Shading had no effect on biomass production or side-shoot production but increased height increment in all three species. It also increased the C and N proportions of total dry mass but decreased C:N ratio in the capitula. (3 Neighbours of a different species reduced biomass and side-shoot production in the two hummock species but had no effect on the hollow species. (4 All three species showed interaction between shading and neighbour in two or more plant traits. S. fallax showed competitive advantage over S. palustre in no-shading treatments and over S. capillifolium in moderate shading treatments. In addition, under deep shading, S. fallax showed a competitive advantage over both hummock species. A clear competitive hierarchy S. fallax>S. capillifolium>S. palustre emerged which was consistent with the hierarchy of side-shoot production. (5 The results suggest that all the species appear to tolerate deep shade (for a few months at least. In a shaded environment, especially under deeply shaded conditions, S. fallax retains its dominance in hollow habitats (if water availability is guaranteed by virtue of its advantage in side-shoot production. (6 If shading increases then the abundance of different Sphagnum species is likely to change.

  4. [Effects of noise competition on monosyllabic and disyllabic word perception in children].

    Science.gov (United States)

    Liu, H H; Liu, S; Li, Y; Zheng, Z P; Jin, X; Li, J; Ren, C C; Zheng, J; Zhang, J; Chen, M; Hao, J S; Yang, Y; Liu, W; Ni, X

    2017-05-07

    Objective: The purpose of the present study was to investigate the effects of noise competition on word perception in normal hearing (NH) children and children with cochlear implantation (CI). Methods: To estimate the contribution of noise competition on speech perception, word perception in speech-shaped noise(SSN)and 4-talker babble noise(BN) with Mandarin Lexical Neighborhood Test were performed in 80 NH children and 89 children with CI. Corrected perception percentages were acquired in each group. Results: Both signal to noise ratio (SNR) and noise type influenced the word perception. In NH group, corrected percentages of disyllabic word perception in SSN were 24.2%, 55.9%, 77.1%, 85.1% and 88.9% at -8, -4, 0, 4 and 8 dB SNR, corresponding corrected percentages of monosyllabic word were 13.9%, 39.5%, 60.1%, 68.8% and 80.1%, respectively. In BN noise, corrected percentages of disyllabic word were 2.4%, 24.3%, 55.6%, 74.3% and 86.2%, corresponding monosyllabic word were 2.3%, 20.8%, 47.2%, 61.1% and 74.8%, respectively. In CI group, corrected percentages of dissyllabic word in SSN and BN at 10 dB SNR were 65.5% and 58.1%, respectively. Corresponding monosyllabic word were 49.0% and 41.0%. For SNR=5 dB, corrected percentages of disyllabic word in SSN and BN were 50.0% and 38.1%, corresponding corrected percentages of monosyllabic word were 40.8% and 25.1%, respectively. Analysis indicated that the masking effect were significantly higher in BN compared with SSN. Conclusions: Noise competition influence word perception performance significantly. In specific, the influence of noise on word perception is bigger in children with CI than in NH children. The masking effect is higher in BN noise when compared with SSN.

  5. Do electoral rules matter? Electoral list models and their effects on party competition and institutional performance

    Directory of Open Access Journals (Sweden)

    André Marenco dos Santos

    Full Text Available This study is intended to analyze the effects of different electoral list models, classified in two basic groups: electoral rules for proportional representation which either (1 reserve the parties the monopoly of electoral ranking or (2 provide for intra-partisan competition according to preferential votes as the procedure for defining the final make-up of the party's membership in the Legislature. The article examines 51 national cases, seeking to evaluate the consequences of different types of lists on both the party systems' dynamics and institutional performance. The results show that after controlling for other variables, electoral lists are insufficient to explain the observed differences between the respective democracies.

  6. The Effect of Serial Culture and Storage on the Protective Potential of a Competitive Exclusion Preparation

    Directory of Open Access Journals (Sweden)

    Almeida WAF

    2002-01-01

    Full Text Available The competitive exclusion method (EC was used to protect day-old birds against colonisation of the intestinal tract by Salmonella enterica serovar Enteritidis (SE. The culture prepared in nutrient broth incubated at 37ºC/24 h inhibited SE growth in the caecal contents. The beneficial effect was also observed after serial passage of the feces culture for up to 14 times. The material obtained after 12 serial sub-cultures after storage for 28 days at 4-6ºC also kept its action on SE.

  7. Chemical defense lowers plant competitiveness.

    Science.gov (United States)

    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.

  8. Optimizing methyl-eugenol aromatherapy to maximize posttreatment effects to enhance mating competitiveness of male Bactrocera carambolae (Diptera: Tephritidae).

    Science.gov (United States)

    Haq, Ihsan ul; Vreysen, Marc J B; Cacéres, Carlos; Shelly, Todd E; Hendrichs, Jorge

    2015-10-01

    Methyl-eugenol (ME) (1,2-dimethoxy-4-(2-propenyl)benzene), a natural phytochemical, did enhance male Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae) mating competitiveness 3 d after ingestion. Enhanced male mating competitiveness can significantly increase the effectiveness of the sterile insect technique (SIT). ME application to mass reared sterile flies by feeding is infeasible. ME application by aromatherapy however, would be a very practical way of ME application in fly emergence and release facilities. This approach was shown to enhance mating competitiveness of B. carambolae 3 d posttreatment (DPT). Despite this added benefit, every additional day of delaying release will reduce sterile fly quality and will add cost to SIT application. The present study was planned to assess the effects of ME-aromatherapy on male B. carambolae mating competitiveness 1DPT and 2DPT. ME aromatherapy 1DPT or 2DPT did enhance mating competitiveness of B. carambolae males whereas ME feeding 1DPT and 2DPT did not. Male mating competitiveness was enhanced by the ME aromatherapy irrespective if they received 1DPT, 2DPT or 3DPT. ME aromatherapy, being a viable approach for its application, did enhance mating competitiveness of male B. carambolae 1 d posttreatment as ME feeding did 3 d after ingestion. ©2014 The Authors Journal compliation © Insititute of Zoology, Chinese Academy of Science.

  9. Detrimental effects of an autosomal selfish genetic element on sperm competitiveness in house mice.

    Science.gov (United States)

    Sutter, Andreas; Lindholm, Anna K

    2015-07-22

    Female multiple mating (polyandry) is widespread across many animal taxa and indirect genetic benefits are a major evolutionary force favouring polyandry. An incentive for polyandry arises when multiple mating leads to sperm competition that disadvantages sperm from genetically inferior mates. A reduction in genetic quality is associated with costly selfish genetic elements (SGEs), and studies in invertebrates have shown that males bearing sex ratio distorting SGEs are worse sperm competitors than wild-type males.We used a vertebrate model species to test whether females can avoid an autosomal SGE, the t haplotype, through polyandry. The t haplotype inhouse mice exhibits strong drive in t heterozygous males by affecting spermatogenesis and is associated with homozygous in utero lethality. We used controlled matings to test the effect of the t haplotype on sperm competitiveness. Regardless of mating order, t heterozygous males sired only 11% of zygotes when competing against wild-type males, suggesting a very strong effect of the t haplotype on sperm quality. We provide, to our knowledge,the first substantial evidence that polyandry ameliorates the harmful effects of an autosomal SGE arising through genetic incompatibility. We discuss potential mechanisms in our study species and the broader implications for the benefits of polyandry.

  10. Combined effects of predator cues and competition define habitat choice and food consumption of amphipod mesograzers.

    Science.gov (United States)

    Beermann, Jan; Boos, Karin; Gutow, Lars; Boersma, Maarten; Peralta, Ana Carolina

    2018-03-01

    Predation has direct impact on prey populations by reducing prey abundance. In addition, predator presence alone can also have non-consumptive effects on prey species, potentially influencing their interspecific interactions and thus the structure of entire assemblages. The performance of potential prey species may, therefore, depend on both the presence of predators and competitors. We studied habitat use and food consumption of a marine mesograzer, the amphipod Echinogammarus marinus, in the presence/absence of a fish mesopredator and/or an amphipod competitor. The presence of the predator affected both habitat choice and food consumption of the grazer, indicating a trade-off between the use of predator-free space and food acquisition. Without the predator, E. marinus were distributed equally over different microhabitats, whereas in the presence of the predator, most individuals chose a sheltered microhabitat and reduced their food consumption. Furthermore, habitat choice of the amphipods changed in the presence of interspecific competitors, also resulting in reduced feeding rates. The performance of E. marinus is apparently driven by trait-mediated direct and indirect effects caused by the interplay of predator avoidance and competition. This highlights the importance of potential non-consumptive impacts of predators on their prey organisms. The flexible responses of small invertebrate consumers to the combined effects of predation and competition potentially lead to changes in the structure of coastal ecosystems and the multiple species interactions therein.

  11. Home Versus Away Competition: Effect on Psychophysiological Variables in Elite Rugby Union.

    Science.gov (United States)

    Cunniffe, Brian; Morgan, Kevin A; Baker, Julien S; Cardinale, Marco; Davies, Bruce

    2015-09-01

    This study evaluated the effect of game venue and starting status on precompetitive psychophysiological measures in elite rugby union. Saliva samples were taken from players (starting XV, n = 15, and nonstarters, n = 9) on a control day and 90 min before 4 games played consecutively at home and away venues against local rivals and league leaders. Precompetition psychological states were assessed using the Competitive State Anxiety Inventory-2. The squad recorded 2 wins (home) and 2 losses (away) over the study period. Calculated effect sizes (ESs) showed higher pregame cortisol- (C) and testosterone- (T) difference values before all games than on a baseline control day (ES 0.7-1.5). Similar findings were observed for cognitive and somatic anxiety. Small between-venues C differences were observed in starting XV players (ES 0.2-0.25). Conversely, lower home T- (ES 0.95) and higher away C- (ES 0.6) difference values were observed in nonstarters. Lower T-difference values were apparent in nonstarters (vs starting XV) before home games, providing evidence of a between-groups effect (ES 0.92). Findings show an anticipatory rise in psychophysiological variables before competition. Knowledge of starting status appears a moderating factor in the magnitude of player endocrine response between home and away games.

  12. Accounting for variation in root wood density and percent carbon in belowground carbon estimates

    Science.gov (United States)

    Brandon H. Namm; John-Pascal Berrill

    2012-01-01

    Little is known about belowground biomass and carbon in tanoak. Although tanoaks rarely provide merchantable wood, an assessment of belowground carbon loss due to tanoak removal and Sudden Oak Death will inform conservation and management decisions in redwood-tanoak ecosystems.The carbon content of woody biomass is a function of...

  13. The response of belowground carbon allocation in forests to global change

    Science.gov (United States)

    Christian P. Giardina; Mark Coleman; Dan Binkley; Jessica Hancock; John S. King; Erik Lilleskov; Wendy M. Loya; Kurt S. Pregitzer; Michael G. Ryan; Carl Trettin

    2005-01-01

    Belowground carbon allocation (BCA) in forests regulates soil organic matter formation and influences biotic and abiotic properties of soil such as bulk density, cation exchange capacity, and water holding capacity. On a global scale, the total quantity of carbon allocated belowground by terrestrial plants is enormous, exceeding by an order of magnitude the quantity of...

  14. Use of belowground growing degree days to predict rooting of dormant hardwood cuttings of Populus

    Science.gov (United States)

    R.S., Jr. Zalesny; E.O. Bauer; D.E. Riemenschneider

    2004-01-01

    Planting Populus cuttings based on calendar days neglects soil temperature extremes and does not promote rooting based on specific genotypes. Our objectives were to: 1) test the biological efficacy of a thermal index based on belowground growing degree days (GDD) across the growing period, 2) test for interactions between belowground GDD and clones,...

  15. Effects of regulation and economic environment on the electricity industry's competitiveness: A study based on OECD countries

    International Nuclear Information System (INIS)

    Baek, Chulwoo; Jung, Euy-Young; Lee, Jeong-Dong

    2014-01-01

    We propose a competitiveness index for the electricity industry based on efficiency, stability, and growth factors identified from previous studies subject to data accessibility. These are then weighted appropriately through the application of the analytical hierarchy process. This index is an alternative tool to capture the diverse characteristics of the electricity industry in order to analyze performance after deregulation. Using the competitiveness index, we analyze the effect of regulation change in specific economic environments represented by the level of economic development, energy intensity, and manufacturing share, for example. According to the results, deregulation generally increases competitiveness, but the effect depends on the economic environment and the type of regulation. Deregulating entry and vertical integration to increase competitiveness is more effective in countries where the level of economic development, energy intensity, and manufacturing share are low. The manner in which the privatization effect is related to the economic environment is, however, unclear. - Highlights: • This study proposes a competitiveness index for the electricity industry. • It examines the effects of electricity industry deregulation in OECD countries. • It suggests an economic environment in which deregulation can contribute to competitiveness

  16. Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age

    NARCIS (Netherlands)

    Brinkman, E.P.; Duyts, H.; Van der Putten, W.H.

    2005-01-01

    We studied the effects of intra- and interspecific competition on the abundance of endoparasitic nematodes and assessed the consequences for biomass production of the natural dune grass Ammophila arenaria. Pratylenchus penetrans was limited by intraspecific competition and it suppressed the

  17. Relative-age effect on competition outcomes at the World Youth and World Junior Athletics Championships.

    Science.gov (United States)

    Hollings, Stephen C; Hume, Patria A; Hopkins, Will G

    2014-01-01

    The relative-age effect refers to a higher frequency of athletes with birthdates earlier in the competitive year. Track and field athletics has a 2-year competitive cycle at youth and junior levels that could make it particularly susceptible to the effect. We have therefore investigated the effect in athletics event finalists (first to eighth place) at the 2008 Junior Championships (men and women aged ≤ 19 years; n=1479) and the 2009 Youth Championships (boys and girls aged 16-17 years; n=1445). Counts of finalists differing in age by 1 year were estimated with Poisson regression and compared as factor effects (with ×/÷ 90% confidence limits and assessment of magnitude). The factor effects were: junior men 2.1 (×/÷ 1.4, large); junior women 1.7 (×/÷ 1.4, moderate); youth boys 3.7 (×/÷ 1.4, very large); youth girls 2.1 (×/÷ 1.3, large). Analysis by event group indicated the age effect was greatest in youth boys' sprints & hurdles (4.0, ×/÷ 1.7, very large), throws (7.2, ×/÷ 2.3, very large) and jumps (5.6, ×/÷ 1.9, very large), whereas it was smallest in junior men's throws (1.4, ×/÷ 1.4, small) and youth girls' jumps (1.4, ×/÷ 1.4, small). In conclusion, the marked relative-age effects in athletics must exclude some talented younger athletes from youth and junior championships and presumably discourage them from continuing to senior championships. The consequences are a lower overall standard of performance and, for some athletes, termination of involvement in athletics before realising their full potential. An alternative structure and calendar is needed to make youth and junior athletics championships more equitable.

  18. The effect of counter-trading on competition in electricity markets

    NARCIS (Netherlands)

    Dijk, J.J.; Willems, B.

    2011-01-01

    In a competitive electricity market, nodal pricing is the most efficient way to manage congestion. Counter-trading is inefficient as it gives the wrong long term signals for entry and exit of power plants. However, in a non-competitive market, additional entry will improve the competitiveness of the

  19. Tumor evolution in space: the effects of competition colonization tradeoffs on tumor invasion dynamics

    Directory of Open Access Journals (Sweden)

    Paul A Orlando

    2013-03-01

    Full Text Available We apply competition colonization tradeoff models to tumor growth and invasion dynamics to explore the hypothesis that varying selection forces will result in predictable phenotypic differences in cells at the tumor invasive front compared to those in the core. Spatially, ecologically, and evolutionarily explicit partial differential equation models of tumor growth confirm that spatial invasion produces selection pressure for motile phenotypes. The effects of the invasive phenotype on normal adjacent tissue determine the patterns of growth and phenotype distribution. If tumor cells do not destroy their environment, colonizer and competitive phenotypes coexist with the former localized at the invasion front and the latter, to the tumor interior. If tumors cells do destroy their environment, then cell motility is strongly selected resulting in accelerated invasion speed with time. Our results suggest that the widely observed genetic heterogeneity within cancers may not be the stochastic effect of random mutations. Rather, it may be the consequence of predictable variations in environmental selection forces and corresponding phenotypic adaptations.

  20. The effect of marketing knowledge management on sustainable competitive advantage: Evidence from banking industry

    Directory of Open Access Journals (Sweden)

    Fatemeh Rezaee

    2017-11-01

    Full Text Available Nowadays, the importance of achieving sustainable organization with competitive advantage in complex environments has many researchers’ interest. So, in this study, we evaluate different views of MKM and its role to reach SCA within banking industry. This research is relatively the scarce empirical study and adds to its originality. The findings offer valuable insights on the generalizability of MKM in a research setting. In fact, the purpose of this study is to empirically test the effect of the marketing knowledge management (MKM on sustainable competitive advantage (SCA within banking industry of Iran. A valid research instrument was utilized to conduct a survey of 150 top- and middle-level managers from Mellat bank of Iran (MBI. With a response rate of 81.3 percent, 122 questionnaires were returned; the number of valid and usable questionnaires was 101. Using exploratory and confirmatory factor analyses, MKM were classified into organizational strategies, culture and performance of senior manager, information technology (IT, research and development (R & D, internal customer (personnel, and external customer (client. Moreover, MBI’ SCA was classified into three dimensions: market, customer, finance. Structural equation modelling was utilized to test the stated hypotheses and model. Statistical support was found for the hypothesized relationships. Moreover it has been shown that MKM maintained the greatest effect on the market centered SCA, while it had the least influence on the customer centered.

  1. Can We Predict the Winner in a Market with Network Effects? Competition in Cryptocurrency Market

    Directory of Open Access Journals (Sweden)

    Neil Gandal

    2016-07-01

    Full Text Available We analyze how network effects affect competition in the nascent cryptocurrency market. We do so by examining early dynamics of exchange rates among different cryptocurrencies. While Bitcoin essentially dominates this market, our data suggest no evidence of a winner-take-all effect early in the market. Indeed, for a relatively long period, a few other cryptocurrencies competing with Bitcoin (the early industry leader appreciated much more quickly than Bitcoin. The data in this period are consistent with the use of cryptocurrencies as financial assets (popularized by Bitcoin, and not consistent with winner-take-all dynamics. Toward the end of our sample, however, things change dramatically. Bitcoin appreciates against the USD, while other currencies depreciate against the USD. The data in this period are consistent with strong network effects and winner-take-all dynamics. This trend continues at the time of writing.

  2. Changes in Soil Carbon Stocks and Fluxes in Response to Altered Above- and Belowground Vegetation Inputs

    Science.gov (United States)

    Marañón-Jiménez, S.; Schuetze, C.; Cuntz, M.; García-Quirós, I.; Dienstbach, L.; Schrumpf, M.; Rebmann, C.

    2016-12-01

    The stimulation of vegetation productivity in response to rising atmospheric CO2 concentrations can potentially compensate climate change feedbacks. However, this will depend on the allocation of C resources of vegetation into biomass production versus root exudates and on the feedbacks with soil microorganisms. These dynamic adjustments of vegetation will result on changes in above- and belowground productivity and on the amount of C exported to root exudates. Consequent alteration of litter and rhizosphere detritus inputs to the soil and their interaction on controlling soil C sequestration capacity has been, however, rarely assessed. We hypothesize that above- and belowground vegetation exert a synergistic control of soil CO2 emissions, and that the activation of soil organic matter mineralization by the addition of labile organic substrates (i.e.: the priming effect) is altered by changes in the amount and in the quality of the carbon inputs. In order to elucidate these questions, different levels of litter addition were implemented on trenched (root exclusion) and non-trenched plots (with roots) in a temperate deciduous forest. Changes in the sensitivity of soil respiration to temperature and moisture were detected by measuring CO2 fluxes continuously at high temporal resolution with automatic chambers, whereas the spatial and seasonal variability was determined using portable chambers. Annual changes in soil carbon and nitrogen stocks provide additional information on the soil carbon sequestration in response to above- and belowground inputs. Both roots and litter inputs significantly enhanced soil CO2 effluxes soon after the implementation of the experiment. We detected synergistic effects between roots and litter inputs on soil CO2 emissions: When roots were present, carbon mineralized in response to litter addition was much higher than the total amount of carbon added in litter (ca. 170 g C m-2 y-1). Preliminary results of this study suggest that labile

  3. Using simulation models to investigate the cumulative effects of sowing rate, sowing date and cultivar choice on weed competition.

    Science.gov (United States)

    Andrew, Izzadora K S; Storkey, Jonathan

    2017-05-01

    With the increasing pressure on crop production from the evolution of herbicide resistance, farmers are increasingly adopting Integrated Weed Management (IWM) strategies to augment their weed control. These include measures to increase the competitiveness of the crop canopy such as increased sowing rate and the use of more competitive cultivars. While there are data on the relative impact of these non-chemical weed control methods assessed in isolation, there is uncertainty about their combined contribution, which may be hindering their adoption. In this article, the INTERCOM simulation model of crop/weed competition was used to examine the combined impact of crop density, sowing date and cultivar choice on the outcomes of competition between wheat ( Triticum aestivum ) and Alopecurus myosuroides . Alopecurus myosuroides is a problematic weed of cereal crops in North-Western Europe and the primary target for IWM in the UK because it has evolved resistance to a range of herbicides. The model was parameterised for two cultivars with contrasting competitive ability, and simulations run across 10 years at different crop densities and two sowing dates. The results suggest that sowing date, sowing density and cultivar choice largely work in a complementary fashion, allowing enhanced competitive ability against weeds when used in combination. However, the relative benefit of choosing a more competitive cultivar decreases at later sowing dates and higher crop densities. Modeling approaches could be further employed to examine the effectiveness of IWM, reducing the need for more expensive and cumbersome long-term in situ experimentation.

  4. EFFECTS OF HIGHER EDUCATION ON GLOBAL COMPETITIVENESS: REVIEWS IN RELATION WITH EUROPEAN COUNTRIES AND THE MIDDLE EAST COUNTRIES

    Directory of Open Access Journals (Sweden)

    HILAL YILDIRIR KESER

    2015-03-01

    Full Text Available The aim of this study is investigate the effects of higher education on global competitiveness One of the most widely accepted definition of global competitiveness is in the form of " efficiency level encompassing all of the institutions that will ensure sustainable growth in a country, policies and factors of production". Therefore the competitiveness of a country depends on the factors such as; The level of development of R & D activities and productivity, performance of various sectors, the country's trade surplus, producing goods hosting high-tech in their nature, availability of expert and skilled labor force. But one of the main points in the realization of these factors is the quality of the higher education. Higher education has an important role in the formation of qualified labour. And the qualified labour carries the competitiveness firstly of the sector and then of the country up to higher ranks by increasing the performance and productivity of the companies. The study will be discussed in the following way: firstly the context of the global competitiveness will be mentioned, secondly, the role and importance of higher education will be put forth by explaining the basic determinants of competitivenes particularly within the World Economic Forum Global Competitiveness Index. Finally, assessments will be made in relation with the situation of higher education in global competitiveness in European countries and Middle Eastern countries.

  5. Interactive effects of plant-available soil silicon and herbivory on competition between two grass species

    Science.gov (United States)

    Garbuzov, Mihail; Reidinger, Stefan; Hartley, Susan E.

    2011-01-01

    Background and Aims The herbivore defence system of true grasses (Poaceae) is predominantly based on silicon that is taken up from the soil and deposited in the leaves in the form of abrasive phytoliths. Silicon uptake mechanisms can be both passive and active, with the latter suggesting that there is an energetic cost to silicon uptake. This study assessed the effects of plant-available soil silicon and herbivory on the competitive interactions between the grasses Poa annua, a species that has previously been reported to accumulate only small amounts of silicon, and Lolium perenne, a high silicon accumulator. Methods Plants were grown in mono- and mixed cultures under greenhouse conditions. Plant-available soil silicon levels were manipulated by adding silicon to the soil in the form of sodium silicate. Subsets of mixed culture pots were exposed to above-ground herbivory by desert locusts (Schistocerca gregaria). Key Results In the absence of herbivory, silicon addition increased biomass of P. annua but decreased biomass of L. perenne. Silicon addition increased foliar silicon concentrations of both grass species >4-fold. Under low soil-silicon availability the herbivores removed more leaf biomass from L. perenne than from P. annua, whereas under high silicon availability the reverse was true. Consequently, herbivory shifted the competitive balance between the two grass species, with the outcome depending on the availability of soil silicon. Conclusions It is concluded that a complex interplay between herbivore abundance, growth–defence trade-offs and the availability of soil silicon in the grasses' local environment affects the outcome of inter-specific competition, and so has the potential to impact on plant community structure. PMID:21868406

  6. Total Belowground Carbon Allocation in a Fast-growing Eucalyptus Plantation Estimated Using a Carbon Balance Approach

    Science.gov (United States)

    Christian P. Giardina; Michael G. Ryan

    2002-01-01

    Trees allocate a large portion of gross primary production belowground for the production and maintenance of roots and mycorrhizae. The difficulty of directly measuring total belowground carbon allocation (TBCA) has limited our understanding of belowground carbon (C) cycling and the factors that control this important flux. We measured TBCA over 4 years using a...

  7. It's in the Game: The effect of Competition and Cooperation on Anti-Social Behavior in Online Video Games

    OpenAIRE

    McLean, David Parsons

    2016-01-01

    Video games have been criticized for the amount of violence present in them and how this violence could affect aggression and anti-social behavior. Much of the literature on video games effects has focused primarily on the content of video games, but recent studies show that competition in video games could be a major influence on aggression. While competing against other players has been shown to increase aggression, there is less research on whether the mere presence of a competitive enviro...

  8. Effects of Intraspecific Competition and Host-Parasitoid Developmental Timing on Foraging Behaviour of a Parasitoid Wasp

    OpenAIRE

    Couchoux, Christelle; van Nouhuys, Saskya

    2014-01-01

    In a context where hosts are distributed in patches and susceptible to parasitism for a limited time, female parasitoids foraging for hosts might experience intraspecific competition. We investigated the effects of host and parasitoid developmental stage and intraspecific competition among foraging females on host-searching behaviour in the parasitoid wasp Hyposoter horticola. We found that H. horticola females have a pre-reproductive adult stage during which their eggs are not mature yet and...

  9. Rhizosphere priming effects on soil carbon and nitrogen dynamics among tree species with and without intraspecific competition.

    Science.gov (United States)

    Yin, Liming; Dijkstra, Feike A; Wang, Peng; Zhu, Biao; Cheng, Weixin

    2018-03-07

    Rhizosphere priming effects (RPEs) play a central role in modifying soil organic matter mineralization. However, effects of tree species and intraspecific competition on RPEs are poorly understood. We investigated RPEs of three tree species (larch, ash and Chinese fir) and the impact of intraspecific competition of these species on the RPE by growing them at two planting densities for 140 d. We determined the RPE on soil organic carbon (C) decomposition, gross and net nitrogen (N) mineralization and net plant N acquisition. Differences in the RPE among species were associated with differences in plant biomass. Gross N mineralization and net plant N acquisition increased, but net N mineralization decreased, as the RPE on soil organic C decomposition increased. Intraspecific competition reduced the RPE on soil organic C decomposition, gross and net N mineralization, and net plant N acquisition, especially for ash and Chinese fir. Microbial N mining may explain the overall positive RPEs across species, whereas intensified plant-microbe competition for N may have reduced the RPE with intraspecific competition. Overall, the species-specific effects of tree species play an important role in modulating the magnitude and mechanisms of RPEs and the intraspecific competition on soil C and N dynamics. © 2018 The Authors New Phytologist © 2018 New Phytologist Trust.

  10. Effects of intra- and interspecific competition on the sensitivity of Daphnia magna populations to the fungicide carbendazim.

    Science.gov (United States)

    Del Arco, Ana Isabel; Rico, Andreu; van den Brink, Paul J

    2015-08-01

    The ecological risk assessment of pesticides is generally based on toxicity data obtained from single-species laboratory experiments and does not take into account ecological interactions such as competition or predation. Intraspecific and interspecific competition are expected to result in additional stress and might increase the sensitivity of aquatic populations to pesticide contamination. To test this hypothesis, the effects of the fungicide carbendazim were assessed on the population dynamics of the micro-crustacean Daphnia magna under different levels of intraspecific and interspecific competition for an algal food resource, using the rotifer Brachionus calyciflorus as competing species. The experiments were performed in glass jars with three different carbendazim concentrations (i.e., 50, 100 and 150 µg/L), and had a duration of 25 days, with a 4-day pre-treatment period in which competition was allowed to take place and a 21-day exposure period. The endpoints evaluated were D. magna total population abundance and population structure. Results of these experiments show that competition stress on its own had a significant influence on shaping D. magna population's structure, however, a different response was observed in the intraspecific and interspecific competition experiments. The use of a 4-day pre-treatment period in the intraspecific experiment already led to an absence of interactive effects due to the quick abundance confluence between the different intraspecific treatments, thus not allowing the observation of interactive effects between competition and carbendazim stress. Results of the interspecific competition experiment showed that rotifers were quickly outcompeted by D. magna and that D. magna even profited from the rotifer presence through exploitative competition, which alleviated the original stress caused by the algal resource limitation. These experiments suggest that competition interactions play an important role in defining population

  11. Disruption of a belowground mutualism alters interactions between plants and their floral visitors.

    Science.gov (United States)

    Cahill, James F; Elle, Elizabeth; Smith, Glen R; Shore, Bryon H

    2008-07-01

    Plants engage in diverse and intimate interactions with unrelated taxa. For example, aboveground floral visitors provide pollination services, while belowground arbuscular mycorrhizal fungi (AMF) enhance nutrient capture. Traditionally in ecology, these processes were studied in isolation, reinforcing the prevailing assumption that these above- and belowground processes were also functionally distinct. More recently, there has been a growing realization that the soil surface is not a barrier to many ecological interactions, particularly those involving plants (who live simultaneously above and below ground). Because of the potentially large impact that mycorrhizae and floral visitors can have on plant performance and community dynamics, we designed an experiment to test whether these multi-species mutualisms were interdependent under field conditions. Using benomyl, a widely used fungicide, we suppressed AMF in a native grassland, measuring plant, fungal, and floral-visitor responses after three years of fungal suppression. AMF suppression caused a shift in the community of floral visitors from large-bodied bees to small-bodied bees and flies, and reduced the total number of floral visits per flowering stem 67% across the 23 flowering species found in the plots. Fungal suppression has species-specific effects on floral visits for the six most common flowering plants in this experiment. Exploratory analyses suggest these results were due to changes in floral-visitor behavior due to altered patch-level floral display, rather than through direct effects of AMF suppression on floral morphology. Our findings indicate that AMF are an important, and overlooked, driver of floral-visitor community structure with the potential to affect pollination services. These results support the growing body of research indicating that interactions among ecological interactions can be of meaningful effect size under natural field conditions and may influence individual performance

  12. Quantifying above- and belowground biomass carbon loss with forest conversion in tropical lowlands of Sumatra (Indonesia).

    Science.gov (United States)

    Kotowska, Martyna M; Leuschner, Christoph; Triadiati, Triadiati; Meriem, Selis; Hertel, Dietrich

    2015-10-01

    Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPPtotal ) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPPtotal in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha(-1) ) was more than two times higher than in jungle rubber stands (147 Mg ha(-1) ) and >four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha(-1) ). NPPtotal was higher in the natural forest (24 Mg ha(-1)  yr(-1) ) than in the rubber systems (20 and 15 Mg ha(-1)  yr(-1) ), but was highest in the oil palm system (33 Mg ha(-1)  yr(-1) ) due to very high fruit production (15-20 Mg ha(-1)  yr(-1) ). NPPtotal was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha(-1) ) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations. © 2015 John Wiley & Sons Ltd.

  13. A broadleaf species enhances an autotoxic conifers growth through belowground chemical interactions.

    Science.gov (United States)

    Xia, Zhi-Chao; Kong, Chui-Hua; Chen, Long-Chi; Wang, Peng; Wang, Si-Long

    2016-09-01

    Plants may affect the performance of neighboring plants either positively or negatively through interspecific and intraspecific interactions. Productivity of mixed-species systems is ultimately the net result of positive and negative interactions among the component species. Despite increasing knowledge of positive interactions occurring in mixed-species tree systems, relatively little is known about the mechanisms underlying such interactions. Based on data from 25-year-old experimental stands in situ and a series of controlled experiments, we test the hypothesis that a broadleaf, non-N fixing species, Michelia macclurei, facilitates the performance of an autotoxic conifer Chinese fir (Cunninghamia lanceolata) through belowground chemical interactions. Chinese fir roots released the allelochemical cyclic dipeptide (6-hydroxy-1,3-dimethyl-8-nonadecyl-[1,4]-diazocane- 2,5-diketone) into the soil environment, resulting in self-growth inhibition, and deterioration of soil microorganisms that improve P availability. However, when grown with M. macclurei the growth of Chinese fir was consistently enhanced. In particular, Chinese fir enhanced root growth and distribution in deep soil layers. When compared with monocultures of Chinese fir, the presence of M. macclurei reduced release and increased degradation of cyclic dipeptide in the soil, resulting in a shift from self-inhibition to chemical facilitation. This association also improved the soil microbial community by increasing arbuscular mycorrhizal fungi, and induced the production of Chinese fir roots. We conclude that interspecific interactions are less negative than intraspecific ones between non-N fixing broadleaf and autotoxic conifer species. The impacts are generated by reducing allelochemical levels, enhancing belowground mutualisms, improving soil properties, and changing root distributions as well as the net effects of all the processes within the soil. In particular, allelochemical context alters the

  14. Effect of crop density on competition by wheat and barley with Agrostemma githago and other weeds

    DEFF Research Database (Denmark)

    Doll, H.; Holm, U.; Søgaard, B.

    1995-01-01

    The effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density....... The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley...... had a better competitive ability than A. githago. Wheat and A. githago utilized resources for growth better when grown in mixture than when grown in pure stands as the relative yield totals were significantly larger than unity....

  15. PHARMACEUTICAL PRICING IN EMERGING MARKETS: EFFECTS OF INCOME, COMPETITION, AND PROCUREMENT

    Science.gov (United States)

    Danzon, Patricia M; Mulcahy, Andrew W; Towse, Adrian K

    2015-01-01

    This paper analyzes determinants of ex-manufacturer prices for originator and generic drugs across countries. We focus on drugs to treat HIV/AIDS, TB, and malaria in middle and low-income countries (MLICs), with robustness checks to other therapeutic categories and the full income range of countries. We examine the effects of per capita income, income dispersion, competition from originator and generic substitutes, and whether the drugs are sold to retail pharmacies versus tendered procurement by non-government organizations. The cross-national income elasticity of prices is 0.27 across the full income range of countries but is 0.0–0.10 between MLICs, implying that drugs are least affordable relative to income in the lowest income countries. Within-country income inequality contributes to relatively high prices in MLICs. Although generics are priced roughly 30% lower than originators on average, the variance is large. Additional generic competitors only weakly affect prices, plausibly because generic quality uncertainty leads to competition on brand rather than price. Tendered procurement that imposes quality standards attracts multinational generic suppliers and significantly reduces prices of originator and generic drugs, compared with their respective prices to retail pharmacies. ©2013 The Authors. Health Economics Published by John Wiley & Sons Ltd. PMID:24293058

  16. Male antenna morphology and its effect on scramble competition in false garden mantids

    Science.gov (United States)

    Jayaweera, Anuradhi; Barry, Katherine L.

    2017-10-01

    Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

  17. Technology management-An effective tool to add competitiveness to the business

    Energy Technology Data Exchange (ETDEWEB)

    Layrisse, I.; Izquierdo, A. [Intevep, S.A., Caracas (Venezuela)

    1996-08-01

    Petreleos de Venezuela (PDVSA) and its affiliated companies, aware of the importance of the technology to sustain the viability of a successful corporation in global markets with increasing competition and stringent economies, are devoting important efforts in technology as an effective tool to add competitiveness to its core businesses. These efforts are based in the conception of the technology as a structural aspect of the corporation integrated to each one of its businesses. In this sense technology is considered in an integrated way together with markets, operations, infrastructure, resources, etc., across the value chain of the company, from the conception of its vision and mission to the formulation and execution of its operating plans. In this presentation, the conceptual and methodological aspects employed by PDVSA in the establishment of its technology strategy integrated to its business plan, and subsequent project portfolio definition, are summarized. The experience acquired through this corporative exercise conducted by PDVSA confirms that technology and its management are highly linked to the culture of the companies and of the countries where they operate. The technology management best practices are very helpful in establishing processes and specific methodologies; however, the consideration of other aspects such as leadership, management style, shared values, etc., need to be taken into account with the same emphasis, in order to accomplish the changes needed to create a technology culture fitted to a given setting and ideology.

  18. HIV competition dynamics over sexual networks: first comer advantage conserves founder effects.

    Science.gov (United States)

    Ferdinandy, Bence; Mones, Enys; Vicsek, Tamás; Müller, Viktor

    2015-02-01

    Outside Africa, the global phylogeography of HIV is characterized by compartmentalized local epidemics that are typically dominated by a single subtype, which indicates strong founder effects. We hypothesized that the competition of viral strains at the epidemic level may involve an advantage of the resident strain that was the first to colonize a population. Such an effect would slow down the invasion of new strains, and thus also the diversification of the epidemic. We developed a stochastic modelling framework to simulate HIV epidemics over dynamic contact networks. We simulated epidemics in which the second strain was introduced into a population where the first strain had established a steady-state epidemic, and assessed whether, and on what time scale, the second strain was able to spread in the population. Simulations were parameterized based on empirical data; we tested scenarios with varying levels of overall prevalence. The spread of the second strain occurred on a much slower time scale compared with the initial expansion of the first strain. With strains of equal transmission efficiency, the second strain was unable to invade on a time scale relevant for the history of the HIV pandemic. To become dominant over a time scale of decades, the second strain needed considerable (>25%) advantage in transmission efficiency over the resident strain. The inhibition effect was weaker if the second strain was introduced while the first strain was still in its growth phase. We also tested how possible mechanisms of interference (inhibition of superinfection, depletion of highly connected hubs in the network, one-time acute peak of infectiousness) contribute to the inhibition effect. Our simulations confirmed a strong first comer advantage in the competition dynamics of HIV at the population level, which may explain the global phylogeography of the virus and may influence the future evolution of the pandemic.

  19. HIV competition dynamics over sexual networks: first comer advantage conserves founder effects.

    Directory of Open Access Journals (Sweden)

    Bence Ferdinandy

    2015-02-01

    Full Text Available Outside Africa, the global phylogeography of HIV is characterized by compartmentalized local epidemics that are typically dominated by a single subtype, which indicates strong founder effects. We hypothesized that the competition of viral strains at the epidemic level may involve an advantage of the resident strain that was the first to colonize a population. Such an effect would slow down the invasion of new strains, and thus also the diversification of the epidemic. We developed a stochastic modelling framework to simulate HIV epidemics over dynamic contact networks. We simulated epidemics in which the second strain was introduced into a population where the first strain had established a steady-state epidemic, and assessed whether, and on what time scale, the second strain was able to spread in the population. Simulations were parameterized based on empirical data; we tested scenarios with varying levels of overall prevalence. The spread of the second strain occurred on a much slower time scale compared with the initial expansion of the first strain. With strains of equal transmission efficiency, the second strain was unable to invade on a time scale relevant for the history of the HIV pandemic. To become dominant over a time scale of decades, the second strain needed considerable (>25% advantage in transmission efficiency over the resident strain. The inhibition effect was weaker if the second strain was introduced while the first strain was still in its growth phase. We also tested how possible mechanisms of interference (inhibition of superinfection, depletion of highly connected hubs in the network, one-time acute peak of infectiousness contribute to the inhibition effect. Our simulations confirmed a strong first comer advantage in the competition dynamics of HIV at the population level, which may explain the global phylogeography of the virus and may influence the future evolution of the pandemic.

  20. Cardenolides, induced responses, and interactions between above- and belowground herbivores of milkweed (Asclepias spp.).

    Science.gov (United States)

    Rasmann, Sergio; Agrawal, Anurag A; Cook, Susan C; Erwin, Alexis C

    2009-09-01

    Theory has long predicted allocation patterns for plant defense against herbivory, but only recently have both above- and belowground plant defenses been considered simultaneously. Milkweeds in the genus Asclepias are a classic chemically defended clade of plants with toxic cardenolides (cardiac glycosides) and pressurized latex employed as anti-herbivore weapons. Here we combine a comparative approach to investigate broadscale patterns in allocation to root vs. shoot defenses across species with a species-specific experimental approach to identify the consequences of defense allocational shifts on a specialist herbivore. Our results show phylogenetic conservatism for inducibility of shoot cardenolides by an aboveground herbivore, with only four closely related tropical species showing significant induction; the eight temperate species examined were not inducible. Allocation to root and shoot cardenolides was positively correlated across species, and this relationship was maintained after accounting for phylogenetic nonindependence. In contrast to long-standing theoretical predictions, we found no evidence for a trade-off between constitutive and induced cardenolides; indeed the two were positively correlated across species in both roots and shoots. Finally, specialist root and shoot herbivores of common milkweed (A. syriaca) had opposing effects on latex production, and these effects had consequences for caterpillar growth consistent with latex providing resistance. Although cardenolides were not affected by our treatments, A. syriaca allocated 40% more cardenolides to shoots over roots. We conclude that constitutive and inducible defenses are not trading off across plant species, and shoots of Asclepias are more inducible than roots. Phylogenetic conservatism cannot explain the observed patterns of cardenolide levels across species, but inducibility per se was conserved in a tropical clade. Finally, given that above- and belowground herbivores can systemically

  1. Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition

    NARCIS (Netherlands)

    Huang, Chengdong; Liu, Quanqing; Gou, Fang; Li, Xiaolin; Zhang, Chaochun; Werf, van der Wopke; Zhang, Fusuo

    2017-01-01

    Intercropping is a promising model for ecological intensification of modern agriculture. Little information is available on how species growth patterns are affected by size-asymmetric above- and belowground competitive interactions, especially in intercrops with more than two species. We studied

  2. Serial-position effects in preference construction: a sensitivity analysis of the pairwise-competition model.

    Science.gov (United States)

    Canic, Emina; Pachur, Thorsten

    2014-01-01

    People have a stronger preference for options encountered earlier or later in a sequence than for options in the middle of the sequence. To account for these primacy and recency effects, Mantonakis et al. (2009) sketched a sequential updating mechanism, the pairwise-competition model. We propose a formal instantiation of the model and, using computer simulations, examine how the sizes of the predicted primacy and recency effects are affected by (a) variability in the quality of the options; (b) the number of options presented (sequence length); (c) the level of choice inertia (i.e., the tendency to stick with the current favorite); and (d) whether choice inertia dynamically increases over the sequence. We find that recency effects are reduced and primacy effects are increased with variability in quality as compared to without, and that this holds regardless of sequence length. A sizeable primacy effect occurs only with relatively short sequences or rather high levels of choice inertia. Dynamic inertia increases primacy effects and reduces recency effects, and the impact increases with higher inertia levels. We relate these results to empirical findings and derive novel predictions from the model.

  3. Serial-Position Effects in Preference Construction: A Sensitivity Analysis of the Pairwise-Competition Model

    Directory of Open Access Journals (Sweden)

    Emina eCanic

    2014-08-01

    Full Text Available People have a stronger preference for options encountered earlier or later in a sequence than for options in the middle of the sequence. To account for these primacy and recency effects, Mantonakis, Rodero, Lesschaeve, and Hastie (2009 sketched a sequential updating mechanism, the pairwise-competition model. We propose a formal instantiation of the model and, using computer simulations, examine how the sizes of the predicted primacy and recency effects are affected by (a variability in the quality of the options; (b the number of options presented (sequence length; (c the level of choice inertia (i.e., the tendency to stick with the current favorite; and (d whether choice inertia dynamically increases over the sequence. We find that recency effects are reduced and primacy effects are increased with variability in quality as compared to without, and that this holds regardless of sequence length. A sizeable primacy effect occurs only with relatively short sequences or rather high levels of choice inertia. Dynamic inertia increases primacy effects and reduces recency effects, and the impact increases with higher inertia levels. We relate these results to empirical findings and derive novel predictions from the model.

  4. Photomorphogenic effects of UV-B radiation on plants: consequences for light competition

    International Nuclear Information System (INIS)

    Barnes, P.W.; Ballaré, C.L.; Caldwell, M.M.

    1996-01-01

    A combination of field and labotatory studies were conducted to explore the nature of photomorphogenic effects of ultraviolet-B radiation (UV-B; 280–320 nm) on plant morphology and to evaluate the ecological consequences of these alterations in morphology for interspecific competition. Under laboratory conditions, seedlings of cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) exhibited appreciable (ca. 50%) and rapid (< 3h) inhibition in hypocotyl elongation in response to UV-B exposure. In cucumber, this inhibition was reversible, occurred without any associated changes in dry matter production and was caused by UV-B incident on the cotyledons and not the stem or growing tip. Inhibition of stem elongation in etiolated tomato seedlings occurred at least 3 h prior to the onset of accumulation of UV-absorbing pigments and monochromatic UV supplied against a background of visible radiation revealed maximum effectiveness in inhibition around 300 nm. Collectively, these findings suggest that a specific, but yet unidentified, UV-B photoreceptor is involved in mediating certain morphological responses to UV-B. For mixtures of wheat (Triticum aestivum L.) and wild oat (Avena fatua L.), a common weedy competitor, supplemental UV-B irradiation in the field differentially altered shoot morphology which resulted in changes in canopy structure, light interception and calculated stand photosynthesis. It is argued that, because of its asymmetrical nature, competition for light can potentially amplify the effects of UV-B on shoot morphology and may, therefore, be an important mechanism by which changes in the solar UV-B spectrum associated with stratospheric ozone reduction could alter the composition and character of terrestrial vegetation

  5. Verb bias and verb-specific competition effects on sentence production.

    Science.gov (United States)

    Thothathiri, Malathi; Evans, Daniel G; Poudel, Sonali

    2017-01-01

    How do speakers choose between structural options for expressing a given meaning? Overall preference for some structures over others as well as prior statistical association between specific verbs and sentence structures ("verb bias") are known to broadly influence language use. However, the effects of prior statistical experience on the planning and execution of utterances and the mechanisms that facilitate structural choice for verbs with different biases have not been fully explored. In this study, we manipulated verb bias for English double-object (DO) and prepositional-object (PO) dative structures: some verbs appeared solely in the DO structure (DO-only), others solely in PO (PO-only) and yet others equally in both (Equi). Structural choices during subsequent free-choice sentence production revealed the expected dispreference for DO overall but critically also a reliable linear trend in DO production that was consistent with verb bias (DO-only > Equi > PO-only). Going beyond the general verb bias effect, three results suggested that Equi verbs, which were associated equally with the two structures, engendered verb-specific competition and required additional resources for choosing the dispreferred DO structure. First, DO production with Equi verbs but not the other verbs correlated with participants' inhibition ability. Second, utterance duration prior to the choice of a DO structure showed a quadratic trend (DO-only PO-only) with the longest durations for Equi verbs. Third, eye movements consistent with reimagining the event also showed a quadratic trend (DO-only PO-only) prior to choosing DO, suggesting that participants used such recall particularly for Equi verbs. Together, these analyses of structural choices, utterance durations, eye movements and individual differences in executive functions shed light on the effects of verb bias and verb-specific competition on sentence production and the role of different executive functions in choosing between

  6. Competition between two wetland macrophytes under different levels of sediment saturation

    Directory of Open Access Journals (Sweden)

    Feng Li

    2015-02-01

    Full Text Available Plant-plant interactions have been widely studied under various environmental conditions. However, in wetland ecosystems how plant interactions change in response to variation in sediment saturation remains largely unclear, even though different levels of sediment saturation play important roles in determining plant growth performance in wetland ecosystems. To this end, a competition experiment with two typical wetland species, Carex brevicuspis (neighbor plant and Polygonum hydropiper (target plant, was conducted in a target-neighbor design. Two water levels (0 cm and -40 cm water levels representing waterlogged and drained sediments, respectively and three neighbor plant densities (0 plants m-2, 400 plants m-2, and 1600 plants m-2 were tested in a factorial design. Biomass accumulation of P. hydropiper decreased along with enhanced C. brevicuspis density in the waterlogged treatment. However, in the drained treatment, biomass accumulation did not change under two C. brevicuspis densities. Above-ground relative neighbor effect index (ARNE and relative neighbor effect index (RNE of C. brevicuspis on P. hydropiper increased along with enhanced C. brevicuspis density only under waterlogged conditions. The below-ground relative neighbor effect index (BRNE was not affected at the different water level and density treatments. The below-ground mass fraction of P. hydropiper was much higher in the waterlogged treatment than it was in the drained one, especially with no C. brevicuspis treatment. However, the leaf mass fraction displayed the opposite pattern. The longest root length of P. hydropiper was much shorter under waterlogged treatment than under the drained treatment. These results suggest that the competition intensity of C. brevicuspis to P. hydropiper increased along with increasing C. brevicuspis density only under waterlogged conditions. Moreover, this study also confirms that P. hydropiper can acclimate to water stress mainly through

  7. The Effect of Competitive Rivalry on Internal Communication in Private Healthcare Organizations: Evidence from Istanbul, Turkey

    Directory of Open Access Journals (Sweden)

    Gültekin Altuntas

    2014-02-01

    Full Text Available Both competitive rivalry and internal communication play a crucial role for a business to position itself in a favourable manner in order to succeed particularly in a hostile environment. While numerous studies present the importance of competitive rivalry and of communication, even internal communication separately, little is known about the specific linkage of how competitive rivalry affects communication in the literature. Within the framework of internal communication, this study focuses on the notion that competitive rivalry is related to the path and style of communication as well as to the usage of internal communication tools but not to quality of communication. Thus, our research presents the linkage and the interaction between competitive rivalry and internal communication, of which the results indicate that, overall, competitive rivalry has a significant direct positive influence on internal communication dimensions in terms of path, style and quality of communication, as well as usage of communication tools in healthcare organizations.

  8. Effects of Caffeine Ingestion on Skill Performance During an International Female Rugby Sevens Competition.

    Science.gov (United States)

    Portillo, Javier; Del Coso, Juan; Abián-Vicén, Javier

    2017-12-01

    Portillo, J, Del Coso, J, and Abián-Vicén, J. Effects of caffeine ingestion on skill performance during an international female rugby sevens competition. J Strength Cond Res 31(12): 3351-3357, 2017-The aim of this study was to establish the effects of a caffeine-containing energy drink on skills and technical performance during a match in female elite rugby sevens players. On 2 nonconsecutive days of a friendly tournament, 16 women from the Spanish national rugby sevens team (mean age = 23 ± 2 years) ingested 3 mg of caffeine per kilogram of body mass in the form of an energy drink or the same drink without caffeine (placebo drink). After 60 minutes for caffeine absorption, participants played 3 rugby sevens matches against another national team. Body impacts during the matches were assessed by triaxial accelerometers. The matches were videotaped, and each individual technical action was notated afterward by 2 experienced observers. In comparison with the placebo drink, the ingestion of the caffeinated energy drink increased the rate of body impacts in zone 1 (16.1 ± 4.9 vs. 20.8 ± 9.9 impacts/min, p < 0.05), zone 2 (12.2 ± 10.6 vs. 16.2 ± 15.2 impacts/min, p < 0.05), zone 3 (3.8 ± 1.5 vs. 4.7 ± 2.6 impacts/min, p < 0.05), and zone 5 (0.8 ± 0.4 vs. 1.1 ± 0.6 impacts/min, p < 0.05). The pre-exercise ingestion of the caffeinated energy drink did not affect the frequency or the quality of any rugby-specific technical actions during the games. In conclusion, the ingestion of 3 mg·kg of caffeine in the form of an energy drink increased the number of body impacts during a rugby sevens international competition which suggests a higher engagement of the players during the game. However, the caffeine ingestion did not influence the quality of the technical actions performed during the competition.

  9. The effects of goal involvement on moral behavior in an experimentally manipulated competitive setting.

    Science.gov (United States)

    Sage, Luke; Kavussanu, Maria

    2007-04-01

    In this experiment we examined the effects of task and ego involvement on three measures of moral behavior--prosocial choice, observed prosocial behavior, and observed antisocial behavior--in a competitive setting. We also investigated sex differences in moral behavior. Male (n = 48) and female (n = 48) college students were randomly assigned to a task-involving, an ego-involving, or a control condition. Participants played two 10-min games of table soccer and completed measures of prosocial choice, goal involvement, goal orientation, and demographics. The two games were recorded, and frequencies of prosocial and antisocial behavior were coded. Players assigned to the task-involving condition were higher in prosocial choice than those in the ego-involving or control conditions. Individuals in the ego-involving condition displayed more antisocial behaviors than those in the task-involving or control conditions. Finally, females displayed more prosocial behaviors than males.

  10. The Stroop effect at 80: The competition between stimulus control and cognitive control.

    Science.gov (United States)

    Washburn, David A

    2016-01-01

    For more than 80 years, researchers have examined the interference between automatic processing of stimuli, such as the meaning of color words, on performance of a controlled-processing task such as naming the color in which words are printed. The Stroop effect and its many variations provide an ideal test platform for examining the competition between stimulus control and cognitive control of attention, as reflected in behavior. The two experiments reported here show that rhesus monkeys, like human adults, show interference from incongruous stimulus conditions in a number-Stroop task, and that the monkeys may be particularly susceptible to influence from response strength and less able, relative to human adults, of using executive attention to minimize this interference. © 2016 Society for the Experimental Analysis of Behavior.

  11. The Effect of Competitive Rivalry on Internal Communication in Private Healthcare Organizations: Evidence from Istanbul, Turkey

    OpenAIRE

    Gültekin Altuntas; Fatih Semerciöz; Aral Noyan

    2014-01-01

    Both competitive rivalry and internal communication play a crucial role for a business to position itself in a favourable manner in order to succeed particularly in a hostile environment. While numerous studies present the importance of competitive rivalry and of communication, even internal communication separately, little is known about the specific linkage of how competitive rivalry affects communication in the literature. Within the framework of internal communication, this study focuses ...

  12. Belowground carbon dynamics in loblolly pine (Pinus taeda) immediately following diammonium phosphate fertilization.

    Science.gov (United States)

    Gough, Christopher M; Seiler, John R

    2004-07-01

    Forest soils store an immense quantity of labile carbon (C) and a may be a large potential sink for atmospheric C. Forest management practices such as fertilization may enhance overall C storage in soils, yet changes in physiological processes following nutrient amendments have not been widely investigated. We intensively monitored belowground C dynamics for nearly 200 days following diammonium phosphate fertilization of pot-grown loblolly pine (Pinus taeda L.) seedlings in an effort to examine the short-term effects of fertilization on processes involved in soil C sequestration. Soil respiration rates initially increased in fertilized pots relative to controls, followed by a brief reversal in this trend and then a final sustained pattern of elevated rates of soil respiration in the fertilized treatment. Patterns in soil respiration rates over time reflected changes in autotrophic (root) and heterotrophic (microbial) components of soil respiration. Root respiration rates were greater in the fertilized treatment 49 days following fertilization and returned to control rates by the end of the study. In contrast, microbial respiration rates and microbial activity per soil C concentration remained depressed over the same time period. Compared with control seedlings, total root biomass was 27% greater in fertilized seedlings harvested at the end of the study, indicating that the elevated soil respiration rates observed toward the end of the study were a result of increased respiring root biomass. We conclude that fertilization, at least over the short-term, may increase soil C sequestration by increasing belowground biomass production and reducing microbial driven C turnover. Copyright 2004 Heron Publishing

  13. Belowground processes regulate ecosystem nitrogen retention during a multi-year forest dieback event

    Science.gov (United States)

    Nave, L. E.; Le Moine, J.; Gough, C. M.; Vogel, C.; Nadelhoffer, K. J.; Curtis, P.

    2013-12-01

    In the absence of disturbances, forests typically have strong retention capacity for nitrogen (N), which is internally recycled between soil, microbial and plant pools. However, disturbances that trigger senescence or mortality of forest vegetation may alter internal N cycling processes and lead to the loss of ecosystem N retention capacity. Here, we present an assessment of the role played by belowground processes in governing ecosystem N cycling and retention during an experimental disturbance that killed the dominant canopy taxa in a Great Lakes forest over a 4-year period. After applying stem girdling to hasten the age-related senescence of the dominant taxa (Populus and Betula spp.; ~35% of the basal area), we observed a 38% decrease in stand-level allocation of nonstructural carbohydrates to fine roots, which triggered a tenfold increase in the rate of fine root turnover and increased soil NH4+ and NO3- availability. Elevated soil N availability decreased mycorrhizal hyphal foraging and N uptake, effectively down-regulating the role of symbiotic fungi in the N nutrition of the residual (longer-lived) tree taxa. However, even as residual trees took up less N from mycorrhizal sources, their overall N uptake increased and served to offset the loss of the dominant taxa. The net result of this offset was that canopy N stocks remained constant through the disturbance period and there was no appreciable loss of ecosystem N stocks due to leaching or gaseous export. In sum, the cascade of changes in root, microbial, and soil processes during this experiment indicates that these interdependent components of the belowground system comprised a mechanism responsible for retention and redistribution of ecosystem N stocks during the disturbance period.

  14. Interactive effects of interspecific competition and microhabitat on early post-settlement survival in a coral reef fish

    Science.gov (United States)

    Bonin, M. C.; Srinivasan, M.; Almany, G. R.; Jones, G. P.

    2009-03-01

    Microhabitat type and the competition for microhabitats can each influence patterns of abundance and mortality in coral reef fish communities; however, the effect of microhabitat on the intensity and outcome of competition is not well understood. In Kimbe Bay, Papua New Guinea, surveys were used to quantify microhabitat use and selectivity in two live-coral specialist damselfishes (Pomacentridae), Chrysiptera parasema, and Dascyllus melanurus. A patch reef experiment was then conducted to test how intra- and interspecific competition interacts with two types of microhabitat to influence survival of recently settled C. parasema. Surveys demonstrated that C. parasema and D. melanurus recruits utilized similar coral microhabitats; 72% of C. parasema and 85% of D. melanurus used corymbose and bottlebrush growth forms of Acropora. One microhabitat type, Pocillopora sp. coral, was commonly used by D. melanurus but rarely by C. parasema. The patch reef experiment revealed that both microhabitat and interspecific competition influence abundance of recently settled C. parasema. Microhabitat had the strongest influence on survival of C. parasema. In the absence of interspecific competitors, ~85% of C. parasema survived for 5 days after transplantation to high-complexity bottlebrush Acropora reefs when compared to only 25% survival of Pocillopora reefs. In both microhabitats, interspecific competition with D. melanurus, but not intraspecific competition, significantly decreased the survival of C. parasema. Taken together, these results suggest that the observed distribution of C. parasema results from specialized microhabitat requirements and competition for space in those microhabitats. This study demonstrates that interspecific competition and microhabitat type can interact to influence early post-settlement survival in coral reef fishes, though, whether and how these factors influence survival will depend on the behavioural attributes and strength of habitat associations

  15. Competitive Intelligence Practices And Their Effect on Profitability of Firms In The Kenyan Banking Industry

    Directory of Open Access Journals (Sweden)

    JOHN KARANJA NGUGI

    2013-07-01

    Full Text Available The rapidly changing business climate created by advances in technologies, economic and social changes as well as fast-shortening product life cycles, which lead to hyper-competition, demands that firms embrace competitive intelligence as a strategy. This study sought to fill the existing knowledge gap by carrying out an investigation of competitive intelligence practices for greater profitability in the commercial banking industry in Kenya. The management staffs who directly deal with the day to day management of the banks were selected to collect primary data. The study concludes that adoption of competitive intelligence practices affect the profitability of the banking sector.

  16. Cumulative and competitive effects of chemical elements on nuclear glass alteration

    International Nuclear Information System (INIS)

    Arena, Helene

    2016-01-01

    This work takes place in the context of the long-term behavior of nuclear glasses under repository conditions. The main objective is to identify, understand and compare the effects of some chemical elements present in the glass composition and/or in the repository media (Zn, Mg, Ni, Co, Fe, Ca, Gd, Ce, K, Cs, Cr and Ag) on the processes involved in glass alteration by water. The cumulative or competitive nature of the effects of these chemical elements was determined. To reach this goal, a 6 oxides simple glass (ISG) has been altered for more than 500 days in a solution containing one or more of the chemical elements of interest. The results indicate that Zn, Mg, Ni, Co and Fe elements increase glass alteration forming secondary phases with the same structure and stoichiometry (tri-octahedral smectites). To form, these silicates consume chemical elements (Si, Al) from the environment and induce a pH decrease until a limiting value of pH. Beyond this pH the precipitation of secondary phases is inhibited and these chemical elements can be integrated into the gel, replacing Ca whose solubility increases at lower pH. As long as they form secondary phases, the effects of these elements are cumulative. Rare earths Gd and Ce also increase glass alteration forming secondary phases but their effects are lower as they contain less silicon. These elements are not integrated in the gel. Chromium increases glass alteration by precipitating with Ca and leading to a less protective gel, depleted in Ca. Silver precipitates as AgCl and has no effect on the alteration of the glass. The chemical elements K, Cs and Ca limit glass alteration by integrating into the gel and slowing down the transport phenomena therein. This integration is competitive: the order of integration (quantity and effectiveness glass alteration limitation) is the following Ca≥≥Cs≥K. Thus, the increase of glass alteration may be proportional to the quantity of elements promoting the precipitation of

  17. The influence of competition effects on the initial rise method during thermal stimulation of luminescence: A simulation study

    International Nuclear Information System (INIS)

    Kitis, George; Pagonis, Vasilis; Tzamarias, Spyros E.

    2017-01-01

    The initial rise (IR) method is a widely used method to evaluate the activation energy of complex thermoluminescence (TL) glow-curves. It is generally accepted that competition effects take place among the various electrons traps responsible for the TL peaks of a glow curve. In the present study the potential influence of such competition effects on the IR method is studied. The simulation is divided in two parts. In the first part it is assumed that retrapping probabilities are lower than recombination probability. This simulation was carried out assuming either strong or weak competition from a thermally disconnected deep trap (TDDT). In the second part of the simulation the retrapping probabilities are assumed to be greater than the recombination probability. The simulation results showed that competition has serious effects on the resulting glow-curve shapes. Furthermore, the simulation showed that in most cases the IR method is able to reproduce accurately the input values of the activation energies of the three TL peaks. However, it was found that the IR method underestimated the activation energy of the last peak corresponding to the highest temperature by 8–20%, when the retrapping probabilities were higher than the recombination probability. - Highlights: • The IR method is very accurate in single peaks. • In complex TL glow curves the accuracy of IR depends on the competition between active traps. • In presence of strong deep trap competitors the competition between active traps is eliminated. • The IR method is very accurate in absence of competition among active traps. • The IR method underestimates E of an active trap which acts as competitor.

  18. A dynamic perspective on pharmaceutical competition, drug development and cost effectiveness.

    Science.gov (United States)

    Refoios Camejo, Rodrigo; McGrath, Clare; Herings, Ron

    2011-04-01

    Limited healthcare budgets result in payers adopting policies at national, regional or local level to achieve allocative efficiency in drug spending. Some of these aim at creating a link between pharmaceutical prices and the value they provide by setting a cost effectiveness (CE) threshold as the maximum acceptable ratio between incremental costs and effects of new drugs. The clinical effectiveness of the comparator used in those CE analyses tends to be greater over time, whilst, due to market competition and loss of exclusivity, their price is expected to be lower. At the same time, research and development (R&D) costs increase with inflation and with efforts to address regulation towards increased safety concerns. As effective patent times decrease, a minimum price constraint raises for the new entrant. These features occur at different rates across disease areas and are expected to result in differently shaped innovation curves. In this scenario, we demonstrate that a general arbitrary threshold may prevent further efficient R&D. Investment may be withdrawn before the optimum innovation point is reached and affordable clinical effectiveness may be lost. We conclude that disease-specific characteristics are an additional consideration in CE decision rules to accommodate the particularities of innovation across disease areas. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  19. Competitiveness effects of environmental tax reforms (COMETR). Final report to the European Commission, DG Research and DG TAXUD

    Energy Technology Data Exchange (ETDEWEB)

    Skou Andersen, M.; Speck, S. (Univ. of Aarhus, National Environmental Research Institute, Dept. of Policy Analysis (Denmark)); Barker, T.; Junankar, S.; Pollitt, H. (Cambridge Econometrics (United Kingdom)); Fitz Gerald, J.; Scott, S. (Economic and Social Research Institute (Ireland)); Jilkova, J. (Univ. of Economics Prague, Institute for Economic and Environmental Policy (Czech Republic)); Salmons, R.; Ekins, P. (Policy Studies Institute (United Kingdom)); Christie, E.; Michael Landesmann, M. (Vienna Institute for International Economic Studies (Austria))

    2007-12-15

    COMETR provides an ex-post assessment of experiences and competitiveness impacts of using carbon-energy taxes as an instrument of an Environmental Tax Reform (ETR), which shifts the tax burden and helps reduce the carbon emissions that cause global warming. COMETR: reviews the experience in ETR in seven EU Member States (Denmark, Germany, Netherlands, Finland, Slovenia, Sweden and UK); analyses world market conditions for a set of energy-intensive sectors, as a framework for considering competitiveness effects; analyses the effects of ETR on sector-specific energy usage and carbon emissions in Member States with carbon-energy taxes introduced on industry; presents a macroeconomic analysis of the competitiveness effects of ETR for individual Member States as well as for the EU as a whole; provides ex-post figures for environmental decoupling and assesses carbon leakage; reviews mitigation and compensation mechanisms for energy-intensive industries. (au)

  20. Political Failures and Intergovernmental Competition

    Directory of Open Access Journals (Sweden)

    Jean Hindriks

    2012-01-01

    Full Text Available In normative public economics, intergovernmental competition is usually viewed as harmful. Although empirical support for this position does not abound, market integration has intensified competition among developed countries. In this paper we argue that when assessing welfare effects of intergovernmental competition for various forms of political failures (the public choice critique, the outcome is ambiguous and competition can be welfare improving.

  1. Ice-cover effects on competitive interactions between two fish species.

    Science.gov (United States)

    Helland, Ingeborg P; Finstad, Anders G; Forseth, Torbjørn; Hesthagen, Trygve; Ugedal, Ola

    2011-05-01

    1. Variations in the strength of ecological interactions between seasons have received little attention, despite an increased focus on climate alterations on ecosystems. Particularly, the winter situation is often neglected when studying competitive interactions. In northern temperate freshwaters, winter implies low temperatures and reduced food availability, but also strong reduction in ambient light because of ice and snow cover. Here, we study how brown trout [Salmo trutta (L.)] respond to variations in ice-cover duration and competition with Arctic charr [Salvelinus alpinus (L.)], by linking laboratory-derived physiological performance and field data on variation in abundance among and within natural brown trout populations. 2. Both Arctic charr and brown trout reduced resting metabolic rate under simulated ice-cover (darkness) in the laboratory, compared to no ice (6-h daylight). However, in contrast to brown trout, Arctic charr was able to obtain positive growth rate in darkness and had higher food intake in tank experiments than brown trout. Arctic charr also performed better (lower energy loss) under simulated ice-cover in a semi-natural environment with natural food supply. 3. When comparing brown trout biomass across 190 Norwegian lakes along a climate gradient, longer ice-covered duration decreased the biomass only in lakes where brown trout lived together with Arctic charr. We were not able to detect any effect of ice-cover on brown trout biomass in lakes where brown trout was the only fish species. 4. Similarly, a 25-year time series from a lake with both brown trout and Arctic charr showed that brown trout population growth rate depended on the interaction between ice breakup date and Arctic charr abundance. High charr abundance was correlated with low trout population growth rate only in combination with long winters. 5. In conclusion, the two species differed in performance under ice, and the observed outcome of competition in natural populations

  2. The effects of competition on premiums: using United Healthcare's 2015 entry into Affordable Care Act's marketplaces as an instrumental variable.

    Science.gov (United States)

    Agirdas, Cagdas; Krebs, Robert J; Yano, Masato

    2018-01-08

    One goal of the Affordable Care Act is to increase insurance coverage by improving competition and lowering premiums. To facilitate this goal, the federal government enacted online marketplaces in the 395 rating areas spanning 34 states that chose not to establish their own state-run marketplaces. Few multivariate regression studies analyzing the effects of competition on premiums suffer from endogeneity, due to simultaneity and omitted variable biases. However, United Healthcare's decision to enter these marketplaces in 2015 provides the researcher with an opportunity to address this endogeneity problem. Exploiting the variation caused by United Healthcare's entry decision as an instrument for competition, we study the impact of competition on premiums during the first 2 years of these marketplaces. Combining panel data from five different sources and controlling for 12 variables, we find that one more insurer in a rating area leads to a 6.97% reduction in the second-lowest-priced silver plan premium, which is larger than the estimated effects in existing literature. Furthermore, we run a threshold analysis and find that competition's effects on premiums become statistically insignificant if there are four or more insurers in a rating area. These findings are robust to alternative measures of premiums, inclusion of a non-linear term in the regression models and a county-level analysis.

  3. Investigating the Effect of Cooperative Learning and Competitive Learning Strategies on the English Vocabulary Development of Iranian Intermediate EFL Learners

    Science.gov (United States)

    Fekri, Neda

    2016-01-01

    The current study investigated the effect of cooperative and competitive learning strategies on the acquisition of English vocabulary development by Iranian EFL intermediate learners. In addition, it explored what type of theses strategies was more effective. In such doing, utilizing an Oxford Placement Test (OPT), 45 out of 77 Iranian EFL…

  4. EDITORIAL: Physics competitions Physics competitions

    Science.gov (United States)

    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. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems.

    Science.gov (United States)

    Boedecker, Joschka; Lampe, Thomas; Riedmiller, Martin

    2013-01-01

    A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money) are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actually be detrimental to task performance. Furthermore, they have the potential to undermine intrinsic motivation to do an otherwise interesting activity. In this work, we extend a computational model of the dorsomedial and dorsolateral striatal reinforcement learning systems to account for the effects of extrinsic and intrinsic rewards. The model assumes that the brain employs both a goal-directed and a habitual learning system, and competition between both is based on the trade-off between the cost of the reasoning process and value of information. The goal-directed system elicits internal rewards when its models of the environment improve, while the habitual system, being model-free, does not. Our results account for the phenomena that initial extrinsic reward leads to reduced activity after extinction compared to the case without any initial extrinsic rewards, and that performance in complex task settings drops when higher external rewards are promised. We also test the hypothesis that external rewards bias the competition in favor of the computationally efficient, but cruder and less flexible habitual system, which can negatively influence intrinsic motivation and task performance in the class of tasks we consider.

  6. Effects of shoe cleat position on physiology and performance of competitive cyclists.

    Science.gov (United States)

    Paton, Carl D

    2009-12-01

    Aerobic economy is an important factor that affects the performance of competitive cyclists. It has been suggested that placing the foot more anteriorly on the bicycle pedals may improve economy over the traditional foot position by improving pedaling efficiency. The current study examines the effects of changing the anterior-posterior pedal foot position on the physiology and performance of well-trained cyclists. In a crossover study, 10 competitive cyclists completed two maximal incremental and two submaximal tests in either their preferred (control) or a forward (arch) foot position. Maximum oxygen consumption and peak power output were determined from the incremental tests for both foot positions. On two further occasions, cyclists also completed a two-part 60-min submaximal test that required them to maintain a constant power output (equivalent to 60% of their incremental peak power) for 30 min, during which respiratory and blood lactate samples were taken at predetermined intervals. Thereafter, subjects completed a 30-min self-paced maximal effort time trial. Relative to the control, the mean changes (+/-90% confidence limits) in the arch condition were as follows: maximum oxygen consumption, -0.5% (+/-2.0%); incremental peak power output, -0.8% (+/-1.3%); steady-state oxygen consumption at 60%, -2.4% (+/-1.1%); steady-state heart rate 60%, 0.4% (+/-1.7%); lactate concentration 60%, 8.7% (+/-14.4%); and mean time trial power, -1.5% (+/-2.9%). We conclude that there was no substantial physiological or performance advantage in this group using an arch-cleat shoe position in comparison with a cyclist's normal preferred condition.

  7. Effects of available water on growth and competition of southern pine beetle associated fungi

    Science.gov (United States)

    Kier D. Klepzig; J. Flores-Otero; R.W. Hofstetter; M.P. Ayers

    2004-01-01

    Competitive interactions among bark beetle associated fungi are potentially influenced by abiotic factors. Water potential, in particular, undergoes marked changes over the course of beetle colonization of tree hosts. To investigate the impact of water potential on competition among three southern pine beetle associated fungi, Ophiostoma minus,

  8. Effects of the energy and mining industry on management of national competitiveness

    Directory of Open Access Journals (Sweden)

    Peter Madzík

    2016-04-01

    influence of energy and mining industry on competitiveness over the last 40 years has increased, particularly in the case of countries with low or medium economic development, and it has decreased in developed countries. The resulting information about the intensity of the mutual relations might be useful for management of competitiveness and planning of strategic economic tools.

  9. The importance of aboveground-belowground interactions on the evolution and maintenance of variation in plant defence traits

    Directory of Open Access Journals (Sweden)

    Moniek evan Geem

    2013-11-01

    Full Text Available Over the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground - belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite compartments. Less is known about genetic variation in plant traits as this applies to an above- belowground framework. For instance, although the field of genetic variation in aboveground plant traits on community-level interactions is well developed, most studies have ignored genetic variation in plant traits – such as defence - that may have evolved in response to pressures from the combined effects of above- and below ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant- and consumer-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, then multiple attack by antagonists in both domains may lead to trade-offs in where these resources are optimally invested. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top-down control. At larger scales these interactions may generate evolutionary ‘hotspots’ where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed.

  10. Retail competition

    International Nuclear Information System (INIS)

    1998-01-01

    Retail competition as the cornerstone of a competitive electricity marketplace was the subject of the seventh in the series of policy discussion papers developed at the Market Design Conference. Concern was expressed that because of the complexities involved in market design and technical implementation, the retail competition may lag behind other elements of the implementation of the new market design. A variety of key issues were debated, including the role of physical versus financial contracts, the form of retail competition and financial settlement systems in the short term, the requirement to separate 'competitive' (metering, billing, maintenance, consumer education) from non-competitive' (the transmission wires) services and the role of municipal electric utilities. It was agreed that the IMO should play an important role in defining and enforcing the separation of services, and that as a general rule, the development of policy in this area should be guided by the principle of maximizing the potential for competition

  11. Effectiveness of 14-15 years old tennis players’ competition functioning considering correction of their psychological fitness

    Directory of Open Access Journals (Sweden)

    T.B. Makuts

    2015-10-01

    Full Text Available Purpose: to determination influence of individualized psychological training on effectiveness of 14-15 years old tennis players’ competition functioning. Material: in the research 24 tennis players of 14-15 years’ age participated. Individualized psychological training consisted of 15 sessions of total duration of 1.5 months. Results: We substantiated necessity of individualized approach to tennis players’ psychological training. Individual psychological profiles for tennis players, which determined content of psychological training and their selection, were worked out. Informative indicators for assessment of 14-15 years old tennis players’ competition functioning were determined: 1 percentage of won and lost scores at the account of own actions; 2 integral criteria of tennis players’ competition functioning assessment (coefficient of stability and effectiveness; complex indicator of efficiency. Conclusions: it is recommended to consider individual potentials and bents of sportsmen in the course of psychological training.

  12. Competition, Ownership and Productivity

    DEFF Research Database (Denmark)

    Baghdasaryan, Delia; la Cour, Lisbeth

    2013-01-01

    Theoretical results support two concurrent views regarding the mediating role that ownership structure might play on the effect of competition on firm performance. According to one stream of literature, competition has a high, positive impact in companies that have an effective ownership structur...

  13. Effect of competitive interactions between ectomycorrhizal and saprotrophic fungi on Castanea sativa performance.

    Science.gov (United States)

    Pereira, Eric; Coelho, Valentim; Tavares, Rui Manuel; Lino-Neto, Teresa; Baptista, Paula

    2012-01-01

    In Northeast of Portugal, the macrofungal community associated to chestnut tree (Castanea sativa Mill.) is rich and diversified. Among fungal species, the ectomycorrhizal Pisolithus tinctorius and the saprotroph Hypholoma fasciculare are common in this habitat. The aim of the present work was to assess the effect of the interaction between both fungi on growth, nutritional status, and physiology of C. sativa seedlings. In pot experiments, C. sativa seedlings were inoculated with P. tinctorius and H. fasciculare individually or in combination. Inoculation with P. tinctorius stimulated the plant growth and resulted in increased foliar-N, foliar-P, and photosynthetic pigment contents. These effects were suppressed when H. fasciculare was simultaneously applied with P. tinctorius. This result could be related to the inhibition of ectomycorrhizal fungus root colonization as a result of antagonism or to the competition for nutrient sources. If chestnut seedlings have been previously inoculated with P. tinctorius, the subsequent inoculation of H. fasciculare 30 days later did not affect root colonization, and mycorrhization benefits were observed. This work confirms an antagonistic interaction between ectomycorrhizal and saprotrophic fungi with consequences on the ectomycorrhizal host physiology. Although P. tinctorius is effective in promoting growth of host trees by establishing mycorrhizae, in the presence of other fungi, it may not always be able to interact with host roots due to an inability to compete with certain fungi.

  14. Competition in electricity markets

    International Nuclear Information System (INIS)

    Taylor, W.

    1996-01-01

    This article examines expanded wholesale and retail competition and the effect that they are likely to have on the electric power industry. The author believes that expanded wholesale competition is good and will bring immediate benefit to all electric consumers; however, based on the experience of the natural gas industry and the electric power industry in California and other parts of the world, the author counsels caution in moving toward expanded retail competition

  15. THE OPTIMIZATION OF THE TRAINING STRATEGIES IN WHAT CONCERNS OBTAINING A BIGGER TRANSFER OF THE TRAINING EFFECT FOR THE COMPETITION

    Directory of Open Access Journals (Sweden)

    DULGHERU MIRELA

    2010-12-01

    Full Text Available The personal experiences in the position of performance athletes, put us in the situation to do observations about the differences between the segmentary muscular contraction regime during training and theone of the solicitations in the competition effort. In the present paper we want to acknowledge and demonstrate the existence of a competition specific bio-motor (un-metabolic of which if we do not take it into account we risk to have low transfer premises of the training effect towards the competition. In the present paper we usedclassic materials and methods and modern ones of research (the bibliographic study method, the observation method, the logical method, the measurements and recordings method, the graphic method and the experimental one. In our paper we will present the video recorded data of the executions during the competitions and thetraining of an athlete that was part of the investigated subjects’ batch. I put experimentally in evidence the differences in the speed and positions distribution and also in the strengths and speeds distribution during training and competition reaching the conclusion that these differences are obvious and generate changes in thecommands succession. The conclusion that we reached refers to the fact that the administration and regulation process of the physical effort in concordance with the competition effort’s specificity must be revised, known being the fact that because of ignoring the differential nature of the effort’s specificity mistakes are made inchoosing the means and dosages, means are chosen without taking into account the existent differences between the segmentary contraction regime during practice and the one of the solicitations during the competition effort

  16. The effect of size and competition on tree growth rate in old-growth coniferous forests

    Science.gov (United States)

    Das, Adrian

    2012-01-01

    Tree growth and competition play central roles in forest dynamics. Yet models of competition often neglect important variation in species-specific responses. Furthermore, functions used to model changes in growth rate with size do not always allow for potential complexity. Using a large data set from old-growth forests in California, models were parameterized relating growth rate to tree size and competition for four common species. Several functions relating growth rate to size were tested. Competition models included parameters for tree size, competitor size, and competitor distance. Competitive strength was allowed to vary by species. The best ranked models (using Akaike’s information criterion) explained between 18% and 40% of the variance in growth rate, with each species showing a strong response to competition. Models indicated that relationships between competition and growth varied substantially among species. The results also suggested that the relationship between growth rate and tree size can be complex and that how we model it can affect not only our ability to detect that complexity but also whether we obtain misleading results. In this case, for three of four species, the best model captured an apparent and unexpected decline in potential growth rate for the smallest trees in the data set.

  17. Effects of antibacterial dishwashing liquid on foodborne pathogens and competitive microorganisms in kitchen sponges.

    Science.gov (United States)

    Kusumaningrum, H D; van Putten, M M; Rombouts, F M; Beumer, R R

    2002-01-01

    In response to increasing concern about home hygiene, the use of antibacterial products to reduce microorganisms in kitchen sponges and cleaning cloths is strongly promoted by some producers of detergent for domestic use. The effects of an antibacterial dishwashing liquid on Escherichia coli, Salmonella Enteritidis, Staphylococcus aureus, and Bacillus cereus were investigated in a modified suspension test and in used sponges with and without food residues under laboratory conditions. A limited study was conducted in households to assess the efficacy of antibacterial dishwashing liquid as used by the consumer. In the suspension tests, S. aureus and B. cereus were shown to be susceptible to low concentrations of antibacterial dishwashing liquid (0.5%), whereas E. coli and Salmonella Enteritidis maintained their initial numbers for at least 24 h at 25 degrees C. At higher concentrations (2 to 4%), all test organisms decreased to below the detection limit after 24 h. Over a 24-h period, the antibacterial dishwashing liquid did not significantly reduce these organisms in used sponges in which food residues were present. The antibacterial product did not reduce the competitive microorganisms either. Similar results were found for sponges involved in daily household use. The results of this study demonstrate that the antibacterial dishwashing liquid was effective in reducing pathogens in the suspension test but not in the used sponges. This finding indicates that to determine the efficacy of antibacterial products, their use in a household setting must be considered.

  18. The effects of communication between student athletes and physical education teachers on competition success and motivation

    Directory of Open Access Journals (Sweden)

    Bora Mehmet Veysi

    2016-01-01

    Full Text Available This research aimed to explore the effects of communication between student athletes and physical education teachers on competition success and motivation using the parameters such as sport branch, sex, age, and some other variables.The sample group was composed of 631 student athletes (471 male and 160 female attending to secondary schools in Mardin. In order to gather data, “Success Motivation in Sport” Questionnaire developed by Tiryaki and Gödelek (1997, and “Trainers Communication Scale” developed by Abakay and Kuru (2009 were adapted to the students. In order to test data distribution, Kolmogorov-Simirnov test was used. As the data showed a normal distribution according to the ages and service period of the teachers (p=.000<α = 0,05, parametric tests were used for data evaluation. In order to analyze the data, arithmetic averages, One-Way ANOVA, Independent samples t-test were used, and Tukey HSD was used to find out the main reason causing the difference between two variables.As a result, it was found out that the communication skills of the teachers had positive effects on the strength demonstration and gaining success motives of the student athletes. Moreover, students playing Basketball showed a higher degree of perception on this issue when compared to the students attending other sports.

  19. The Effect of Steroid Hormones on the Physical Performance of Boys and Girls During an Olympic Weightlifting Competition.

    Science.gov (United States)

    Crewther, Blair; Obminski, Zbigniew; Cook, Christian

    2016-11-01

    To examine the steroid hormone effect on the physical performance of young athletes during an Olympic weightlifting competition. 26 boys and 26 girls were monitored across 2 weightlifting competitions. Pre- and post-competition testosterone (T), cortisol (C) and dehydroepiandrosterone-sulfate (DHEA-s) were measured in blood, with pre-event free T (FT) and the free androgen index (FAI) calculated. Body mass (BM) and weightlifting performance were recorded. The boys had a larger BM, superior performance with more T, FT and a higher FAI than girls (p < .01). Although C (32%) and DHEA-s (8%) levels were elevated across competition, no sex differences in hormone reactivity were seen. In boys, DHEA-s correlated with performance (r = .46), but not after controlling for BM (r = .14). For girls, T correlated with performance (r = -0.51) after BM was controlled. The sex differences that emerge during puberty were observable, whereby the boys were larger and stronger with a more anabolic profile than girls. Individual DHEA-s (boys) and T (girls) levels were related to performance, but BM appeared to be acting as a mediating (boys) or suppressing (girls) variable. This adds new insight regarding the hormonal contribution to competitive performance in young athletes.

  20. Effects of five years of frequent N additions, with or without acidity, on the growth and below-ground dynamics of a young Sitka spruce stand growing on an acid peat: implications for sustainability

    Directory of Open Access Journals (Sweden)

    L. J. Sheppard

    2004-01-01

    Full Text Available A field manipulation study was established to demonstrate effects of simulated wet N and S deposition on a young (planted 1986 stand of Sitka spruce growing on a predominantly organic soil in an area of low (8–10 kg N ha-1 yr-1 background N deposition in the Scottish borders. From 1996, treatments (six were applied to the canopies of ten-tree plots in each of four blocks. N was provided as NH4NO3, either with H2SO4 (pH 2.5 at 48 or 96 kg N ha-1 yr-1 inputs or without, at 48 kg N ha-1 yr-1 along with wet (rain water and dry controls (scaffolding and a S treatment (Na2SO4. Positive responses (+ >20% over 5 years with respect to stem area increment were measured in response to N inputs, irrespective of whether acid was included. The positive response to N was not dose related and was achieved against falling base cation concentrations in the foliage, particularly with respect to K. The results suggest young trees are able to buffer the low nutrient levels and produce new growth when there is sufficient N. Inputs of 96 kg N ha-1 yr-1, in addition to ambient N inputs, on this site exceeded tree demand resulting in elevated foliar N, N2O losses and measurable soil water N. These excessive N inputs did not reduce stem area growth. Keywords: acid, canopy application, nitrogen, acid organic soil, simulated wet deposition, soil water, sulphur, young Sitka spruce

  1. Above- and Belowground Biomass Allocation in Shrub Biomes across the Northeast Tibetan Plateau

    Science.gov (United States)

    Yang, Yuanhe; Yang, Lucun; Zhou, Guoying

    2016-01-01

    Biomass partitioning has been explored across various biomes. However, the strategies of allocation in plants still remain contentious. This study investigated allocation patterns of above- and belowground biomass at the community level, using biomass survey from the Tibetan Plateau. We explored above- and belowground biomass by conducting three consecutive sampling campaigns across shrub biomes on the northeast Tibetan Plateau during 2011–2013. We then documented the above-ground biomass (AGB), below-ground biomass (BGB) and root: shoot ratio (R/S) and the relationships between R/S and environment factors using data from 201 plots surveyed from 67 sites. We further examined relationships between above-ground and below-ground biomass across various shrub types. Our results indicated that the median values of AGB, BGB, and R/S in Tibetan shrub were 1102.55, 874.91 g m-2, and 0.85, respectively. R/S showed significant trend with mean annual precipitation (MAP), while decreased with mean annual temperature (MAT). Reduced major axis analysis indicated that the slope of the log-log relationship between above- and belowground biomass revealed a significant difference from 1.0 over space, supporting the optimal hypothesis. Interestingly, the slopes of the allometric relationship between log AGB and log BGB differed significantly between alpine and desert shrub. Our findings supported the optimal theory of above- and belowground biomass partitioning in Tibetan shrub, while the isometric hypothesis for alpine shrub at the community level. PMID:27119379

  2. Above- and Belowground Biomass Allocation in Shrub Biomes across the Northeast Tibetan Plateau.

    Science.gov (United States)

    Nie, Xiuqing; Yang, Yuanhe; Yang, Lucun; Zhou, Guoying

    2016-01-01

    Biomass partitioning has been explored across various biomes. However, the strategies of allocation in plants still remain contentious. This study investigated allocation patterns of above- and belowground biomass at the community level, using biomass survey from the Tibetan Plateau. We explored above- and belowground biomass by conducting three consecutive sampling campaigns across shrub biomes on the northeast Tibetan Plateau during 2011-2013. We then documented the above-ground biomass (AGB), below-ground biomass (BGB) and root: shoot ratio (R/S) and the relationships between R/S and environment factors using data from 201 plots surveyed from 67 sites. We further examined relationships between above-ground and below-ground biomass across various shrub types. Our results indicated that the median values of AGB, BGB, and R/S in Tibetan shrub were 1102.55, 874.91 g m-2, and 0.85, respectively. R/S showed significant trend with mean annual precipitation (MAP), while decreased with mean annual temperature (MAT). Reduced major axis analysis indicated that the slope of the log-log relationship between above- and belowground biomass revealed a significant difference from 1.0 over space, supporting the optimal hypothesis. Interestingly, the slopes of the allometric relationship between log AGB and log BGB differed significantly between alpine and desert shrub. Our findings supported the optimal theory of above- and belowground biomass partitioning in Tibetan shrub, while the isometric hypothesis for alpine shrub at the community level.

  3. Above- and Belowground Biomass Allocation in Shrub Biomes across the Northeast Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Xiuqing Nie

    Full Text Available Biomass partitioning has been explored across various biomes. However, the strategies of allocation in plants still remain contentious. This study investigated allocation patterns of above- and belowground biomass at the community level, using biomass survey from the Tibetan Plateau. We explored above- and belowground biomass by conducting three consecutive sampling campaigns across shrub biomes on the northeast Tibetan Plateau during 2011-2013. We then documented the above-ground biomass (AGB, below-ground biomass (BGB and root: shoot ratio (R/S and the relationships between R/S and environment factors using data from 201 plots surveyed from 67 sites. We further examined relationships between above-ground and below-ground biomass across various shrub types. Our results indicated that the median values of AGB, BGB, and R/S in Tibetan shrub were 1102.55, 874.91 g m-2, and 0.85, respectively. R/S showed significant trend with mean annual precipitation (MAP, while decreased with mean annual temperature (MAT. Reduced major axis analysis indicated that the slope of the log-log relationship between above- and belowground biomass revealed a significant difference from 1.0 over space, supporting the optimal hypothesis. Interestingly, the slopes of the allometric relationship between log AGB and log BGB differed significantly between alpine and desert shrub. Our findings supported the optimal theory of above- and belowground biomass partitioning in Tibetan shrub, while the isometric hypothesis for alpine shrub at the community level.

  4. Effects of Intraspecific Competition and Host-Parasitoid Developmental Timing on Foraging Behaviour of a Parasitoid Wasp.

    Science.gov (United States)

    Couchoux, Christelle; van Nouhuys, Saskya

    2014-01-01

    In a context where hosts are distributed in patches and susceptible to parasitism for a limited time, female parasitoids foraging for hosts might experience intraspecific competition. We investigated the effects of host and parasitoid developmental stage and intraspecific competition among foraging females on host-searching behaviour in the parasitoid wasp Hyposoter horticola. We found that H. horticola females have a pre-reproductive adult stage during which their eggs are not mature yet and they forage very little for hosts. The wasps foraged for hosts more once they were mature. Behavioural experiments showed that wasps' foraging activity also increased as host eggs aged and became susceptible to parasitism, and as competition among foraging wasps increased.

  5. The Competitive Effects of the Louisiana Scholarship Program on Public School Performance. Louisiana Scholarship Program Evaluation Report #4. Technical Report

    Science.gov (United States)

    Egalite, Anna J.

    2016-01-01

    Given the significant growth rate and geographic expansion of private school choice programs over the past two decades, it is important to examine how traditional public schools respond to the sudden injection of competition for students and resources. This article uses: (1) a school fixed effects approach; and (2) a regression discontinuity…

  6. Effects of intra- and interspecific competition on diet, growth and behaviour of Labeo calbasu (Hamilton) and Cirrhinus cirrhosus (Bloch)

    NARCIS (Netherlands)

    Rahman, M.M.; Verdegem, M.C.J.

    2010-01-01

    Effects of intra- and interspecific competition on diet, growth, grazing, swimming, resting and social behaviour of two carps calbasu (Labeo calbasu) and mrigal (Cirrhinus cirrhosus) were examined in single and mixed species treatments. Three treatments (tanks with 4 L. calbasu, 4 C. cirrhosus or 2

  7. The Comparative Effect of Using Competitive and Cooperative Learning on the Reading Comprehension of Introvert and Extrovert EFL Learners

    Science.gov (United States)

    Ahour, Touran; Haradasht, Pezhman Nourzad

    2014-01-01

    This study was an attempt to investigate the effect of two types of learning, competitive and cooperative, on the reading comprehension of introvert and extrovert EFL learners. To this end, 120 learners studying at Marefat English Language Institute in Tehran, Iran were selected, after taking a Preliminary English Test (PET), to participate in…

  8. Effects of litters with different concentrations of phenolics on the competition between Calluna vulgaris and Deschampsia flexuosa

    NARCIS (Netherlands)

    Hofland-Zijlstra, J.D.; Berendse, F.

    2010-01-01

    We hypothesized that the outcome of competition between ericaceous plants and grasses is strongly affected by the concentrations of phenolics in the litter that they produce. To test the effect of phenolic-rich litter on soluble soil nitrogen concentrations, plant nitrogen uptake and inter-specific

  9. Political Competitiveness

    OpenAIRE

    Casey B. Mulligan; Kevin K. Tsui

    2006-01-01

    Political competitiveness - which many interpret as the degree of democracy - can be modeled as a monopolistic competition. All regimes are constrained by the threat of "entry," and thereby seek some combination of popular support and political entry barriers. This simple model predicts that many public policies are unrelated to political competitiveness, and that even unchallenged nondemocratic regimes should tax far short of their Laffer curve maximum. Economic sanctions, odious debt repudi...

  10. Aboveground and belowground responses to nutrient additions and herbivore exclusion in Arctic tundra ecosystems in northern Alaska

    Science.gov (United States)

    Moore, J. C.; Gough, L.; Simpson, R.; Johnson, D. R.

    2011-12-01

    declines in top predators. The models revealed shifts in the activities within and between the fungal and bacterial energy pathways, with the treatments inducing a bottleneck in activity at the microbe-microbivore trophic levels within both pathways. Our results confirm the complex nature of aboveground and belowground linkages and interactions in defining ecosystem structure and function. Drivers that enhance plant production and altered plant community structure had direct and indirect effects on the structure and activity within the belowground foodweb, the nature of which can help inform the mechanisms behind C dynamics in response to climate change in the Arctic.

  11. Assessing the Effects of Product Quality and Environmental Management Accounting on the Competitive Advantage of Firms

    Directory of Open Access Journals (Sweden)

    Alan S. Dunk

    2007-03-01

    Full Text Available Arguments have been made in the literature that product quality provides a basis forestablishing and maintaining a firm’s competitive advantage. Proposals suggest that theframework provided by environmental management accounting facilitates product qualityhaving the attributes that are likely to contribute to competitive advantage, and hence it islikely that environmental accounting plays an influential role in that relation. The purpose ofthis study is to examine empirically whether there is evidence for environmental managementaccounting impacting on the relation between product quality and competitive advantage.These findings support the view that environmental management accounting has animportant role to play in firms. Specifically, the results of the study suggest that productquality contributes to a firm’s competitive advantage when the reliance on environmentalmanagement accounting is high. However, it fails to do so when the reliance on environmentalmanagement accounting is low.

  12. The effects of tax competition when politicians create rents to buy political support

    DEFF Research Database (Denmark)

    Eggert, Wolfgang; Sørensen, Peter Birch

    2008-01-01

    We set up a probabilistic voting model to explore the hypothesis that tax competition improves public sector efficiency and social welfare. In the absence of tax base mobility, distortions in the political process induce vote-maximising politicians to create rents to public sector employees....... Allowing tax base mobility may be welfare-enhancing up to a point, because the ensuing tax competition will reduce rents. However, if tax competition is carried too far, it will reduce welfare by causing an underprovision of public goods. Starting from an equilibrium where tax competition has eliminated...... all rents, a coordinated rise in capital taxation will always be welfare-improving. For plausible parameter values it will even be welfare-enhancing to carry tax coordination beyond the point where rents to public sector workers start to emerge...

  13. The Effects of Tax Competition when Politicians Create Rents to Buy Political Support

    DEFF Research Database (Denmark)

    Eggert, Wolfgang; Sørensen, Peter Birch

    We set up a probabilistic voting model to explore the hypothesis that tax competition improves public sector efficiency and social welfare. In the absence of tax base mobility, distortions in the political process induce vote-maximising politicians to create rents to public sector employees....... Allowing tax base mobility may be welfare-enhancing up to a point, because the ensuing tax competition will reduce rents. However, if tax competition is carried too far, it will reduce welfare by causing an underprovision of public goods. Starting from an equilibrium where tax competition has eliminated...... all rents, a coordinated rise in capital taxation will always be welfare-improving. For plausible parameter values it will even be welfare-enhancing to carry tax coordination beyond the point where rents to public sector workers start to emerge...

  14. The Joint Effect of Competition and Complexity on Customer Accounting System Design

    DEFF Research Database (Denmark)

    Holm, Morten; Ax, Christian

    service complexity; (ii) There is a direct positive relationship between customer service complexity and CPA model sophistication; (iii) This positive association is stronger when competition is non-price based than when competition is price based. The study hereby contributes to research on CA design......The importance of measuring customer profitability has recently been reiterated by the management accounting community. However, the stream of research on the factors influencing customer accounting (CA) design choices is still scarce and inconclusive. This paper addresses how the level...... of complexity and competition firms face influences the degree of Customer Profitability Analysis (CPA) Model sophistication. Applying a path analysis on survey data from 217 firms reveals support for three hypotheses: (i) There is an inverted u-shaped relationship between competition intensity and customer...

  15. Effect of seed mixture composition and management on competitiveness of herbs in temporary grasslands

    DEFF Research Database (Denmark)

    Mortensen, Tine Bloch; Søegaard, Karen; Eriksen, Jørgen

    2012-01-01

    In multispecies grasslands the proportion of different herb species may vary considerably due to low competitiveness of some herbs. To examine the possibility for increasing the competitiveness, an experiment with three factors was set up: 1) amount of herb seed (5, 50 or 100%) in a mixture...... (Carum carvi), birdsfoot trefoil (Lotus corniculatus), chervil (Anthriscus cerefolium), plantain (Plantago lanceolata), lucerne (Medicago sativa), and melilot (Melilotus officinalis). All herb species, except lucerne and caraway, were most competitive in the first harvest year. The proportion of all...... herbs, except lucerne, was higher at a 6-cut than at a 4-cut strategy, and application of cattle slurry also affected the competitiveness of the herbs. In general, lucerne, chicory, caraway and plantain were the strongest competitors; salad burnet and birdsfoot trefoil were intermediate; and melilot...

  16. The Joint Effect of Competition and Complexity on Customer Accounting System Design

    DEFF Research Database (Denmark)

    Holm, Morten; Ax, Christian

    The importance of measuring customer profitability has recently been reiterated by the management accounting community. However, the stream of research on the factors influencing customer accounting (CA) design choices is still scarce and inconclusive. This paper addresses how the level...... of complexity and competition firms face influences the degree of Customer Profitability Analysis (CPA) Model sophistication. Applying a path analysis on survey data from 217 firms reveals support for three hypotheses: (i) There is an inverted u-shaped relationship between competition intensity and customer...... service complexity; (ii) There is a direct positive relationship between customer service complexity and CPA model sophistication; (iii) This positive association is stronger when competition is non-price based than when competition is price based. The study hereby contributes to research on CA design...

  17. Effect of larval crowding on mating competitiveness of Anopheles gambiae mosquitoes

    NARCIS (Netherlands)

    Ng'habi, K.R.; John, B.; Nkwengulila, G.; Knols, B.G.J.; Killeen, G.F.; Ferguson, H.M.

    2005-01-01

    Background: The success of sterile or transgenic Anopheles for malaria control depends on their mating competitiveness within wild populations. Current evidence suggests that transgenic mosquitoes have reduced fitness. One means of compensating for this fitness deficit would be to identify

  18. Competition as an Effective Tool in Developing Social Marketing Programs: Driving Behavior Change through Online Activities

    Directory of Open Access Journals (Sweden)

    Corina ŞERBAN

    2011-12-01

    Full Text Available Nowadays, social marketing practices represent an important part of people’s lives. Consumers’ understanding of the need for change has become the top priority for social organizations worldwide. As a result, the number of social marketing programs has increased, making people reflect more on their behaviors and on the need to take action. Competition in social marketing can bring many benefits. The more programs initiated, the more people will start to involve in society’s problems, hereby contributing to beneficial causes. However, social organizations are in the search for competitive advantages to differentiate them on the market. This paper aims to present the role of online communication in driving competitive advantage for social organizations. Using the structural equation model, the paper describes the relations between four characteristics of the online communication: credibility, attractiveness, persuasion and promotion and then presents the correlations between these variables and website competitiveness. The resulting model shows that owning a competitive advantage in social marketing can bring many advantages to both the non-profit organization and the consumer. Therefore, the online environment can be considered a good solution for better serving consumers’ social needs. Its contribution is significant especially in programs for children and adolescents, since teenagers spend more time on the Internet than adults and are more open to using the online channels of communication. In conclusion, this article opens new opportunities for social marketers to address society’s problems and supports the integration of the online communication tools in the competition strategy.

  19. Adverse effects of doping with anabolic androgenic steroids (AAS) in competitive athletics, recreational sports and bodybuilding.

    Science.gov (United States)

    Vorona, Elena; Nieschlag, Eberhard

    2018-02-19

    Despite the fact that sports organizations and legislators have introduced various mechanisms to discourage athletes from using performance and appearance enhancing substances a high percentage of athletes admits to their unabated application. In competitive athletics, bodybuilding and in recreational sports anabolic androgenic steroids (AAS) continue to be the substances most abused. This review summarizes the side effects of AAS abuse on organs and system functions in both sexes. High doses of AAS cause a significant increase of erythrocytes und haemoglobin concentration, which may lead to thromboembolism, intracardiac thrombosis and stroke. Long-term AAS abusers have a higher incidence of arrhythmias, atherosclerosis, concentric left-ventricular myocardial hypertrophy with impaired diastolic function and also sudden cardiac death. Changes of liver function and structure, up to hepatocellular carcinoma, have been described, mainly in cases of chronic misuse of 17α-alkylated AAS. Sleeplessness, increased irritability, depressive mood status are often observed in AAS abuse. In former AAS abusers depression, anxiety and melancholy may persist for many years. Due to negative feedback in the regulation of the hypothalamic-pituitary-gonadal axis AAS can cause reversible suppression of spermatogenesis up to azoospermia. In women the changes most often caused by AAS abuse are hirsutism, irreversible deepening of voice, dysmenorrhoea, secondary amenorrhoea with anovulation and infertility. AAS abuse notwithstanding, under clinical conditions testosterone remains the most important hormone for substitution therapy of male hypogonadism.

  20. Effects of increasing and decreasing physiological arousal on anticipation timing performance during competition and practice.

    Science.gov (United States)

    Duncan, Michael J; Smith, Mike; Bryant, Elizabeth; Eyre, Emma; Cook, Kathryn; Hankey, Joanne; Tallis, Jason; Clarke, Neil; Jones, Marc V

    2016-01-01

    The aim of this study was to investigate if the effects of changes in physiological arousal on timing performance can be accurately predicted by the catastrophe model. Eighteen young adults (8 males, 10 females) volunteered to participate in the study following ethical approval. After familiarisation, coincidence anticipation was measured using the Bassin Anticipation Timer under four incremental exercise conditions: Increasing exercise intensity and low cognitive anxiety, increasing exercise intensity and high cognitive anxiety, decreasing exercise intensity and low cognitive anxiety and decreasing exercise intensity and high cognitive anxiety. Incremental exercise was performed on a treadmill at intensities of 30%, 50%, 70% and 90% heart rate reserve (HRR) respectively. Ratings of cognitive anxiety were taken at each intensity using the Mental Readiness Form 3 (MRF3) followed by performance of coincidence anticipation trials at speeds of 3 and 8 mph. Results indicated significant condition × intensity interactions for absolute error (AE; p = .0001) and MRF cognitive anxiety intensity scores (p = .05). Post hoc analysis indicated that there were no statistically significant differences in AE across exercise intensities in low-cognitive anxiety conditions. In high-cognitive anxiety conditions, timing performance AE was significantly poorer and cognitive anxiety higher at 90% HRR, compared to the other exercise intensities. There was no difference in timing responses at 90% HRR during competitive trials, irrespective of whether exercise intensity was increasing or decreasing. This study suggests that anticipation timing performance is negatively affected when physiological arousal and cognitive anxiety are high.

  1. Effect of Wild Mustard (Sinapis arvensis Competition and Nitrogen Levels on

    Directory of Open Access Journals (Sweden)

    F Soleymani

    2012-06-01

    Full Text Available To investigate the effect of wild mustard plant density and nitrogen fertilizer on morphological characters, yield and yield components of canola a split-plot experiment based on a randomized complete block design with 3 replications was carried out in Bu-Ali Sina university of Hamedan, in 2009. 4 levels of nitrogen fertilization (100, 150, 200 and 250 kgN h-1 were assigned to main-plots and plant density of wild mustard at 5 levels (0, 4, 8, 16 and 32 plants m-2 to the sub-plots. Results showed that the effects of wild mustard competition on yield and components of canola was significant. 32 plants m-2 of wild mustard reduced grain and biologic yield, number of pod per plant, number of seed per pod and 1000seed weight about 28.7, 30, 40.9, 22.2 and 16 percent respectively. With more nitrogen application, number of pod per plant, number of seed per pod, 1000seed weight and grain yield was increased. By increasing nitrogen from 100 to 250 kg ha-1, grain yield was increased more than 53 percent. Increasing density of wild mustard significantly reduced all above mentioned morphological and qualitative characters, except protein percentage. By increasing nitrogen fertilizer, plant height, number of branches per plant, pod length, oil yield and protein percentage of canola were increased significantly. Overall nevertheless negative effect of weed on canola yield, seems that the application 200 kgN/ha in addition to increasing grain yield and canola oil, had less decline in weed interference.

  2. Effects of Competition and Predation by Native Mosquitoes on the North American Invasion of Aedes japonicus japonicus (Diptera: Culicidae).

    Science.gov (United States)

    Freed, T Z; Kesavaraju, B; Leisnham, P T

    2014-11-01

    The success and effects of a biological invasion can be dependent on species interactions with resident competitors and predators. Indirect interactions between competition and predation, such as keystone predation, can influence both invasion success and the impact of an invasive species on resident competitors. The invasive mosquito Aedes japonicus japonicus (Theobald) has been established within the North American range of the indigenous competitor Aedes triseriatus (Say) and indigenous mosquito predator Toxorhynchites rutilus (Coquillett). The effects of Tx. rutilus predation on competition between Ae. j. japonicus and Ae. triseriatus were tested in laboratory microcosms. Consistent with a prior study, there was minimal evidence of competitive asymmetry between Ae. j. japonicus and Ae. triseriatus, with similar effects of intraspecific versus interspecific interactions on both species. Tx. rutilus predation caused high mortality of both Ae. j. japonicus and Ae. triseriatus, and minimized the effects of density-dependent competition. Ae. japonicus females that survived predation had larger adult body sizes than those in treatments without predators. Ae. triseriatus females that survived Tx. rutilus predation were larger and developed quicker than individuals in treatments without predators. Intraspecific competition and predation negatively affected the finite rate of population increase for Ae. j. japonicus, but only affected individual fitness correlates for Ae. triseriatus, indicating that the overall population performance of the invader is more sensitive to these interactions than the native species. Based on these results, we predict that predation is likely to be an important barrier to the establishment and spread of Ae. j. japonicus in tree holes in North America. © 2014 Entomological Society of America.

  3. Pop competitiveness

    OpenAIRE

    Roberto Cellino; Anna Soci

    2002-01-01

    Very few economic terms are used as much as competitiveness in economics. This article deals with the different meanings of competitiveness, at the level of a firm, at the level of the local area, and at the level of the country. It analyzes the problems of consistency among the available definitions and among the indicators used to measurecompetitiveness.

  4. Competitiveness factors

    OpenAIRE

    Popa Liliana-Viorica

    2012-01-01

    Porter's theory supports the idea that, despite the globalization of production and trade, the competitive advantage is created in a national framework, nations, through their institutional, natural, cultural, economic characteristics ultimately determining the development of certain economic activities. The factors considered by Porter as determinants for the competitive advantage are grouped in four categories, the linkages between them being important as well

  5. Seed rate and nitrogen fertilizer effects on wild mustard (Sinapis arvensis L. and winter wheat (Triticum aestivum L. competition

    Directory of Open Access Journals (Sweden)

    karim moosavi

    2009-06-01

    Full Text Available In order to evaluate wild mustard competitive effect on winter wheat, an additive series experiment was conducted in 2000-2001 at Agricultural Research Station of Mashhad University.The experiment had 3 factor: wheat seed rate (175 , 215 and 255 kg/ha, nitrogen rate (150 and 225 kg/ha, and a range of wild mustard densities. Hyperbolic functions was used to describe yield-weed density relationship. Increasing wild mustard density had a negative , asymptotic – type effect on wheat biomass and grain yield. By increasing wheat seed rate , in optimum nitrogen rate , maximum wheat biomas loss has reduced about 51 %. Maximum yield loss has increased from 42.1 % to 50.4 %, as nitrogen rate incrased from optimum to upper optimum rate of wheat. By increasing of wheat seed rate from 175 to 255 kg/ha, maximum tiller number reduction due to high densities of wild mustard, has decreased by 54 %. Reduction of fertile tiller number was mostly occurred at presence of high nitrogen level, thus, reduction of fertile tiller number compared to control in N1 was 18% , while in N2 has increased to 30%. Wild mustard competition has reduced wheat seed number per ear 30% in compare to weed free control. Results show that wheat 1000 seed weight was more affected by nitrogen rate than plant densities. Apparently, in competition with wheat, wild mustard was better able to utilize the added nitrogen and thus gained a competitive adventage over the wheat.

  6. External Costs and Benefits of Energy. Methodologies, Results and Effects on Renewable Energies Competitivity

    International Nuclear Information System (INIS)

    Saez, R.; Cabal, H.; Varela, M.

    1999-01-01

    This study attempts to give a summarised vision of the concept of eternality in energy production, the social and economic usefulness of its evaluation and consideration as support to the political decision-marking in environmental regulation matters, technologies selection of new plants, priorities establishment on energy plans, etc. More relevant environmental externalisation are described, as are the effects on the health, ecosystems, materials and climate, as well as some of the socioeconomic externalisation such as the employment, increase of the GDP and the reduction and depletion of energy resources. Different methodologies used during the last years have been reviewed as well as the principals resulted obtained in the most relevant studies accomplished internationally on this topic. Special mention has deserved the European study National Implementation of the Extern E Methodology in the EU . Results obtained are represented in Table 2 of this study. Also they are exposed, in a summarised way, the results obtained in the evaluation of environmental externalisation of the Spanish electrical system in function of the fuel cycle. In this last case the obtained results are more approximated since have been obtained by extrapolation from the obtained for ten representative plants geographically distributed trough the Peninsula. Finally it has been analysed the influence that the internalization of the external costs of conventional energies can have in the competitiveness and in te market of renewable energy, those which originate less environmental effects and therefore produce much smaller external costs. The mechanisms of internalization and the consideration on the convenience or not of their incorporation in the price of energy have been also discussed. (Author) 30 refs

  7. Effect of Caffeine on Golf Performance and Fatigue during a Competitive Tournament.

    Science.gov (United States)

    Mumford, Petey W; Tribby, Aaron C; Poole, Christopher N; Dalbo, Vincent J; Scanlan, Aaron T; Moon, Jordan R; Roberts, Michael D; Young, Kaelin C

    2016-01-01

    This study aimed to determine the effect of a caffeine-containing supplement on golf-specific performance and fatigue during a 36-hole competitive golf tournament. Twelve male golfers (34.8 ± 13.9 yr, 175.9 ± 9.3 cm, 81.23 ± 13.14 kg) with a United States Golf Association handicap of 3-10 participated in a double-blind, placebo-controlled, crossover design in which they played an 18-hole round of golf on two consecutive days (36-hole tournament) and were randomly assigned to consume a caffeine-containing supplement (CAF) or placebo (PLA). CAF/PLA was consumed before and after nine holes during each 18-hole round. Total score, drive distance, fairways and greens in regulation, first putt distance, HR, breathing rate, peak trunk acceleration, and trunk posture while putting were recorded. Self-perceived ratings of energy, fatigue, alertness and concentration were also recorded. Total score (76.9 ± 8.1 vs 79.4 ± 9.1, P = 0.039), greens in regulation (8.6 ± 3.3 vs 6.9 ± 4.6, P = 0.035), and drive distance (239.9 ± 33.8 vs 233.2 ± 32.4, P = 0.047) were statistically better during the CAF condition compared with those during PLA. Statistically significant main effects for condition (P 0.05). A moderate dose (1.9 ± 0.3 mg · kg(-1)) of caffeine consumed before and during a round of golf improves golf-specific measures of performance and reduces fatigue in skilled golfers.

  8. Competitive responses of seedlings and understory plants in longleaf pine woodlands: separating canopy influences above and below ground

    Science.gov (United States)

    Stephen D. Pecot; Robert J. Mitchell; Brian J. Palik; Barry Moser; J. Kevin Hiers

    2007-01-01

    A trenching study was used to investigate above- and below-ground competition in a longleaf pine (Pinus palustris P. Mill.) woodland. Trenched and nontrenched plots were replicated in the woodland matrix, at gap edges, and in gap centers representing a range of overstory stocking. One-half of each plot received a herbicide treatment to remove the...

  9. The effect of marketing innovation, market orientation, and social capital on competitive advantage and marketing performance: A study in MSMEs of embroidery Central Java Province

    Directory of Open Access Journals (Sweden)

    Ag. Sunarno Handoyo

    2015-12-01

    Full Text Available This study deals with marketing innovation, market orientation, and social capital in affecting the competitive advantage and marketing performance in Micro, Small, and Medium Enterprises (MSMEs of embroidery in Central Java Province. In this respect, this study tried to test and analyze the effect of marketing innovation, market orienta-tion, and social capital on competitive advantage and marketing performance in Micro, Small, and Medium Enterprises (MSMEs of embroidery in Central Java Province. The samples are 150 respondents as the owners of the embroidery business in Central Java Province. The technical analysis used is Structure Equations Modeling with AMOS Software version 22. The results show that: (1 marketing innovation has significant effect on competitive advantage; (2 market orientation has significant effect on competi-tive advantage; (3 social capital has significant effect on competitive advantage; (4 competitive advantage has significant effect on marketing performance; (5 marketing innovation has significant effect on marketing performance; (6 market orientation has significant effect on marketing performance; (7 social capital has no significant effect on marketing performance. The implication of this study is that the MSMEs of embroidery could improve marketing performance by increasing marketing innovation, market orientation, social capital and competitive advantage. This study also shows that competitive advantage is an intervening variable on marketing performance.

  10. The effects of sex ratio on sexual competition in the European lobster.

    Science.gov (United States)

    Debuse; Addison; Reynolds

    1999-11-01

    During the breeding season an individual's access to mates may be affected by operational sex ratios, causing strong variation in mating success. We manipulated adult sex ratios of the European lobster, Homarus gammarus, to test the predictions of models that relate sexual competition to (1) the sex ratio, (2) the time that an individual is not available to mate and (3) 'collateral investment', whereby two males contribute to a single clutch. The model predictions proved to be relatively insensitive to collateral investment. Male-male competition predominated in the male-biased but not in the female-biased sex ratio. This matches the predictions of one model that incorporates an extended period of female receptivity because the time that a male was unavailable to mate was small compared to the time spent by females in cohabitation and parental care. Although females increased their competitiveness when males were in the minority, male competition remained high. The insensitivity of male-male competition to sex ratios may be due to an upper limit to the costs that males can afford when there is a serious risk of injury, preventing males from increasing their aggression when females are in short supply. Copyright 1999 The Association for the Study of Animal Behaviour.

  11. Consequences of the Allee effect and intraspecific competition on population persistence under adverse environmental conditions.

    Science.gov (United States)

    Petrovskii, Sergei; Blackshaw, Rod; Li, Bai-Lian

    2008-02-01

    The impact of intraspecific interactions on ecological stability and population persistence in terms of steady state(s) existence is considered theoretically based on a general competition model. We compare persistence of a structured population consisting of a few interacting (competitive) subpopulations, or groups, to persistence of the corresponding unstructured population. For a general case, we show that if the intra-group competition is stronger than the inter-group competition, then the structured population is less prone to extinction, i.e. it can persist in a parameter range where the unstructured population goes extinct. For a more specific case of a population with hierarchical competition, we show that relative viability of structured and unstructured populations depend on the type of density dependence in the population growth. Namely, while in the case of logistic growth, structured and unstructured populations exhibit equivalent persistence; in the case of Allee dynamics, the persistence of a hierarchically structured population is shown to be higher. We then apply these results to the case of behaviourally structured populations and demonstrate that an extreme form of individual aggression can be beneficial at the population level and enhance population persistence.

  12. The effects of genetic manipulation, dieldrin treatment and irradiation on the mating competitiveness of male Anopheles arabiensis in field cages.

    Science.gov (United States)

    Yamada, Hanano; Vreysen, Marc J B; Gilles, Jeremie R L; Munhenga, Givemore; Damiens, David D

    2014-08-13

    To enable the release of only sterile male Anopheles arabiensis mosquitoes for the sterile insect technique, the genetic background of a wild-type strain was modified to create a genetic sexing strain ANO IPCL1 that was based on a dieldrin resistance mutation. Secondly, the eggs of ANO IPCL1 require treatment with dieldrin to allow complete elimination of female L1 larvae from the production line. Finally, male mosquito pupae need to be treated with an irradiation dose of 75 Gy for sterilization. The effects of these treatments on the competitiveness of male An. arabiensis were studied. The competitiveness of ANO IPCL1 males that were treated either with irradiation or both dieldrin and irradiation, was compared with that of the wild-type strain (An. arabiensis Dongola) at a 1:1 ratio in 5.36 m3 semi-field cages located in a climate-controlled greenhouse. In addition, three irradiated: untreated male ratios were tested in semi-field cages (1:1, 5:1 and 10:1) and their competition for virgin wild-type females was assessed. The ANO IPCL1 males were equally competitive as the wild-type males in this semi-field setting. The ANO IPCL1 males irradiated at 75 Gy were approximately half as competitive as the unirradiated wild-type males. ANO IPCL1 males that had been treated with dieldrin as eggs, and irradiated with 75 Gy as pupae were slightly more competitive than males that were only irradiated. Ratios of 1:1, 5:1 and 10:1 irradiated ANO IPCL1 males: untreated wild-type males resulted in 31, 66 and 81% induced sterility in the female cage population, respectively. An irradiation dose of 75 Gy reduced the competitiveness of male ANO IPCL1 significantly and will need to be compensated by releasing higher numbers of sterile males in the field. However, the dieldrin treatment used to eliminate females appears to have an unexpected radioprotectant effect, however the mechanism is not understood. A sterile to wild-type ratio of 10:1 effectively reduced the population

  13. Expertise Effects in Face-Selective Areas are Robust to Clutter and Diverted Attention, but not to Competition.

    Science.gov (United States)

    McGugin, Rankin Williams; Van Gulick, Ana E; Tamber-Rosenau, Benjamin J; Ross, David A; Gauthier, Isabel

    2015-09-01

    Expertise effects for nonface objects in face-selective brain areas may reflect stable aspects of neuronal selectivity that determine how observers perceive objects. However, bottom-up (e.g., clutter from irrelevant objects) and top-down manipulations (e.g., attentional selection) can influence activity, affecting the link between category selectivity and individual performance. We test the prediction that individual differences expressed as neural expertise effects for cars in face-selective areas are sufficiently stable to survive clutter and manipulations of attention. Additionally, behavioral work and work using event related potentials suggest that expertise effects may not survive competition; we investigate this using functional magnetic resonance imaging. Subjects varying in expertise with cars made 1-back decisions about cars, faces, and objects in displays containing one or 2 objects, with only one category attended. Univariate analyses suggest car expertise effects are robust to clutter, dampened by reducing attention to cars, but nonetheless more robust to manipulations of attention than competition. While univariate expertise effects are severely abolished by competition between cars and faces, multivariate analyses reveal new information related to car expertise. These results demonstrate that signals in face-selective areas predict expertise effects for nonface objects in a variety of conditions, although individual differences may be expressed in different dependent measures depending on task and instructions. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta Forests.

    Directory of Open Access Journals (Sweden)

    Anne C S McIntosh

    Full Text Available Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs and multiple carbon-source substrate-induced respiration (MSIR of the forest floor microbial community environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis showed that two above-ground (mean tree diameter, litter cover and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs properties were associated with variation in understory plant community composition. These results provide

  15. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests.

    Science.gov (United States)

    McIntosh, Anne C S; Macdonald, S Ellen; Quideau, Sylvie A

    2016-01-01

    Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights

  16. The effect of professional dietary counseling: elite basketball players eat healthier during competition days.

    Science.gov (United States)

    Tsoufi, Anastasia; Maraki, Maria I; Dimitrakopoulos, Leonidas; Famisis, Konstantinos; Grammatikopoulou, Maria G

    2017-10-01

    Literature suggests that dietary intake of elite athletes may differ between training and competition days. In addition, despite the importance of nutrition in sports and the popularity of basketball, studies on the diet of basketball players are scarce. Therefore, the aim of the present study was to assess dietary intake and diet quality in training and competition days in a team of elite basketball players receiving daily professional nutritional counseling. One elite basketball team (N.=15) participating in EuroLeague volunteered for the study. The team employed a certified dietitian, responsible for providing individualized nutritional evaluation and counseling, dietary planning and supervision of the diet of all the players. Dietary intake was assessed using 24-hour recalls and the Healthy Eating Index (HEI) was then calculated. All players exhibited adequate (i.e., >80) HEI score (raw and adjusted for energy intake [EI]), on both training and competition days. Although daily energy, carbohydrate and protein intakes were greater during training compared to competition days (26.0 [21.7, 26.4] vs. 19.5 [19.3, 22.1] MJ, 7.6±1.5 vs. 6.8±0.9 g/kg of body weight [BW] and 2.6±0.6 vs. 2.2±0.2 g/kg BW, respectively; all Ptraining compared to competition days (92.9 [82.1, 93.2] vs. 94.0 [94.0, 94.0] and 89.7 [88.4, 89.7] vs. 92.7 [91.7, 92.8], respectively; all P≤0.001) due to lower total grains, whole grains and total vegetables consumption and greater saturated fats consumption (Pbasketball players receiving daily nutritional counseling by certified sports dietitians exhibit adequate diet quality, with the highest possible observed during competition days.

  17. Modeling the effects of nuclear fuel reservoir operation in a competitive electricity market

    OpenAIRE

    Maria Lykidi; Jean-Michel Glachant; Pascal Gourdel

    2010-01-01

    URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/; Documents de travail du Centre d'Economie de la Sorbonne 2010.83 - ISSN : 1955-611X; In many countries, the electricity systems are quitting the vertically integrated monopoly organization for an operation framed by competitive markets. In such a competitive regime one can ask what the optimal operation/management of the nuclear generation set is. We place ourselves in a medium-ter...

  18. COMPETITION AND FACILITATION EFFECTS OF DIFFERENTIAL INTRA-AND INTER-ROW WEED MANAGEMENT IN SUGARCANE

    OpenAIRE

    Martin , J; Chabalier , M; Letourmy , P; Chopart , J.-L; Arhiman , E; Marion , D

    2013-01-01

    International audience; Differential intra-and inter-row weed management can be a mean to reduce herbicide use in sugarcane. In 2011, a field experiment was conducted in La Reunion Island to assess inter-row weed competition. Four inter-row weed competition treatments for a duration of one (T1), two (T2), three (T3) and four (T4) months after planting were compared in a randomized complete block design with 5 replicates; treatment plots were paired with non-weeded inter-row control plots. All...

  19. Drought as a modifier of interaction between adult beech and spruce - impacts on tree water use, C budgets and biotic interactions above- and belowground

    Science.gov (United States)

    Grams, Thorsten

    2017-04-01

    Understanding biotic interactions among tree species with their microbial associates under drought will be crucial for silviculture in meeting ecological challenges of the future. This contribution gives an overview on a project integrating a throughfall-exclusion experiment (TEE) on adult trees with a natural precipitation gradient (PGR) in central European forests. Focus is on drought affecting species interaction above and belowground, including associated ectomycorrhizal (ECM) communities. Study objects are pure and mixed forests dominated by adult European beech and Norway spruce trees (c. 70-years old). At the throughfall-exclusion experiment (TEE), trees are readily accessible via scaffolding and canopy crane (Kranzberg Forest, southern Germany). Effects of experimentally induced, repeated summer drought are assessed with roughly 100 trees assigned to a total of 12 plots (Kranzberg forest ROOF experiment, kroof.wzw.tum.de). The summer drought treatment started in 2014 and was repeated in 2015 and 2106. The focus on species interaction is intensified by a parallel study along a natural precipitation gradient with plot triplets of monocultures and mixed cultures of European beech and Norway spruce at each of the five study sites. Complementary resource use, effects of competitive vs. facilitation and related changes in ECM communities are exemplified for the two tree species of contrasting foliage (i.e. deciduous vs. evergreen) and stomatal sensitivity to drought (i.e. an-isohydric vs. isohydric behavior). At the TEE site, precipitation throughfall was completely excluded from early spring to late fall (i.e. March to November), resulting in pre-dawn leaf water potentials of both beech and spruce as low as -2.5 MPa. Despite significant reductions in growth and rate of photosynthesis by up to 80% under drought, NSC budget of trees was hardly affected. Moreover, phloem functionality, tested as phloem transport velocity through 13C-labeling of recent

  20. The Comparative Effect of Using Competitive and Cooperative Learning on the Reading Comprehension of Introvert and Extrovert EFL Learners

    Directory of Open Access Journals (Sweden)

    Touran Ahour

    2014-08-01

    Full Text Available This study was an attempt to investigate the effect of two types of learning, competitive and cooperative, on the reading comprehension of introvert and extrovert EFL learners. To this end, 120 learners studying at Marefat English Language Institute in Tehran, Iran were selected, after taking a Preliminary English Test (PET, to participate in this quasi-experimental research. The participants  also answered the Eysenck Personality Inventory (EPI to categorize them into two personality types of introverts and extroverts. Therefore, there were four subgroups: 30 introverts and 30 extroverts undergoing the cooperative learning treatment, and 30 introverts and 30 extroverts experiencing the competitive learning treatment. The reading part of the PET was administered as the posttest of the study after each group was exposed to the treatment for 18 sessions in seven weeks. A two-way ANOVA was run on the collected data in the posttest of four groups. The results revealed that while learners generally outperformed in the competitive setting compared to the cooperative one, the extrovert was better off receiving cooperative instruction. Moreover, introverts excelled extroverts in the competitive group. However, there was no difference between the two personality groups in the cooperative situation.

  1. Disturbance and decoupling of belowground carbon and nitrogen cycles in a northern temperate forest

    Science.gov (United States)

    Nave, L. E.; Nadelhoffer, K.; Le Moine, J.; Hardiman, B. S.; Sparks, J. P.; Strahm, B. D.; Munoz, A.; Gough, C. M.; Vogel, C. S.; Curtis, P.

    2011-12-01

    Belowground carbon (C) and nitrogen (N) cycles are tightly coupled in many northern temperate forests. However, disturbances that cause tree mortality can decouple linkages between belowground components of these biogeochemical cycles. We measured a suite of belowground processes following a treatment to accelerate the natural senescence of early-successional dominants in a northern temperate forest, hypothesizing that tree mortality would decrease belowground C allocation, increase belowground N availability and cycling rates, and trigger N leaching in this highly N-limited forest. In the Forest Accelerated Succession ExperimenT, we stem girdled >6700 aspen and birch trees (39% of basal area) on 40 ha of forestland at the University of Michigan Biological Station to test these and other hypotheses related to forest development and biogeochemistry. Here, we present the cascade of changes in belowground C and N cycling that occurred in the first two growing seasons following initiation of FASET in April 2008. Aspen and birch mortality decreased stand-level fine root nonstructural carbohydrate contents, accelerating fine root turnover and causing a net reduction in fine root biomass. These decreases in belowground C allocation and root functioning increased forest floor net NH4+ availability, which accelerated nitrification rates, increased net NO3- availability, and led to small NO3- leaching losses. These belowground perturbations were registered by the forest canopy through shifts in foliar 13C and 15N natural abundances, which indicated water stress among girdled aspens and faster, leakier cycling in a source N pool shared by foliage of all tree species. We interpret the results of this initial disturbance phase of the FASET study in the context of our conceptual model of N availability and ecosystem C storage over longer-term (successional) time scales. We predict that, following minor N leaching losses during disturbance, reorganization of belowground N cycling

  2. Belowground plant development measured with magnetic resonance imaging (MRI): exploiting the potential for non-invasive trait quantification using sugar beet as a proxy

    Science.gov (United States)

    Metzner, Ralf; van Dusschoten, Dagmar; Bühler, Jonas; Schurr, Ulrich; Jahnke, Siegfried

    2014-01-01

    Both structural and functional properties of belowground plant organs are critical for the development and yield of plants but, compared to the shoot, much more difficult to observe due to soil opacity. Many processes concerning the belowground plant performance are not fully understood, in particular spatial and temporal dynamics and their interrelation with environmental factors. We used Magnetic Resonance Imaging (MRI) as a noninvasive method to evaluate which traits can be measured when a complex plant organ is monitored in-vivo while growing in the soil. We chose sugar beet (Beta vulgaris ssp. vulgaris) as a model system. The beet consists mainly of root tissues, is rather complex regarding tissue structure and responses to environmental factors, and thereby a good object to test the applicability of MRI for 3D phenotyping approaches. Over a time period of up to 3 months, traits such as beet morphology or anatomy were followed in the soil and the effect of differently sized pots on beet fresh weight calculated from MRI data was studied. There was a clear positive correlation between the pot size and the increase in fresh weight of a sugar beet over time. Since knowledge of the development of internal beet structures with several concentric cambia, vascular and parenchyma rings is still limited, we consecutively acquired 3D volumetric images on individual plants using the MRI contrast parameter T2 to map the development of rings at the tissue level. This demonstrates that MRI provides versatile protocols to non-invasively measure plant traits in the soil. It opens new avenues to investigate belowground plant performance under adverse environmental conditions such as drought, nutrient shortage, or soil compaction to seek for traits of belowground organs making plants more resilient to stress. PMID:25278947

  3. Belowground plant development measured with magnetic resonance imaging (MRI: exploiting the potential for non-invasive trait quantification using sugar beet as a proxy

    Directory of Open Access Journals (Sweden)

    Ralf eMetzner

    2014-09-01

    Full Text Available Both structural and functional properties of belowground plant organs are critical for the development and yield of plants but, compared to the shoot, much more difficult to observe due to soil opacity. Many processes concerning the belowground plant performance are not fully understood, in particular spatial and temporal dynamics and their interrelation with environmental factors. We used Magnetic Resonance Imaging (MRI as a noninvasive method to evaluate which traits can be measured when a complex plant organ is monitored in-vivo while growing in the soil. We chose sugar beet (Beta vulgaris ssp. vulgaris as a model system. The beet consists mainly of root tissues, is rather complex regarding tissue structure and responses to environmental factors, and thereby a good object to test the applicability of MRI for 3D phenotyping approaches. Over a time period of up to 3 months, traits such as beet morphology or anatomy were followed in the soil and the effect of differently sized pots on beet fresh weight calculated from MRI data was studied. There was a clear positive correlation between the pot size and the increase in fresh weight of a sugar beet over time. Since knowledge of the development of internal beet structures with several concentric cambia, vascular and parenchyma rings is still limited, we consecutively acquired 3D volumetric images on individual plants using the MRI contrast parameter T2 to map the development of rings at the tissue level. This demonstrates that MRI provides versatile protocols to non-invasively measure plant traits in the soil. It opens new avenues to investigate belowground plant performance under adverse environmental conditions such as drought, nutrient shortage or soil compaction to seek for traits of belowground organs making plants more resilient to stress.

  4. Availability and temporal heterogeneity of water supply affect the vertical distribution and mortality of a belowground herbivore and consequently plant growth.

    Directory of Open Access Journals (Sweden)

    Tomonori Tsunoda

    Full Text Available We examined how the volume and temporal heterogeneity of water supply changed the vertical distribution and mortality of a belowground herbivore, and consequently affected plant biomass. Plantago lanceolata (Plantaginaceae seedlings were grown at one per pot under different combinations of water volume (large or small volume and heterogeneity (homogeneous water conditions, watered every day; heterogeneous conditions, watered every 4 days in the presence or absence of a larva of the belowground herbivorous insect, Anomala cuprea (Coleoptera: Scarabaeidae. The larva was confined in different vertical distributions to top feeding zone (top treatment, middle feeding zone (middle treatment, or bottom feeding zone (bottom treatment; alternatively no larva was introduced (control treatment or larval movement was not confined (free treatment. Three-way interaction between water volume, heterogeneity, and the herbivore significantly affected plant biomass. With a large water volume, plant biomass was lower in free treatment than in control treatment regardless of heterogeneity. Plant biomass in free treatment was as low as in top treatment. With a small water volume and in free treatment, plant biomass was low (similar to that under top treatment under homogeneous water conditions but high under heterogeneous ones (similar to that under middle or bottom treatment. Therefore, there was little effect of belowground herbivory on plant growth under heterogeneous water conditions. In other watering regimes, herbivores would be distributed in the shallow soil and reduced root biomass. Herbivore mortality was high with homogeneous application of a large volume or heterogeneous application of a small water volume. Under the large water volume, plant biomass was high in pots in which the herbivore had died. Thus, the combinations of water volume and heterogeneity affected plant growth via the change of a belowground herbivore.

  5. Availability and temporal heterogeneity of water supply affect the vertical distribution and mortality of a belowground herbivore and consequently plant growth.

    Science.gov (United States)

    Tsunoda, Tomonori; Kachi, Naoki; Suzuki, Jun-Ichirou

    2014-01-01

    We examined how the volume and temporal heterogeneity of water supply changed the vertical distribution and mortality of a belowground herbivore, and consequently affected plant biomass. Plantago lanceolata (Plantaginaceae) seedlings were grown at one per pot under different combinations of water volume (large or small volume) and heterogeneity (homogeneous water conditions, watered every day; heterogeneous conditions, watered every 4 days) in the presence or absence of a larva of the belowground herbivorous insect, Anomala cuprea (Coleoptera: Scarabaeidae). The larva was confined in different vertical distributions to top feeding zone (top treatment), middle feeding zone (middle treatment), or bottom feeding zone (bottom treatment); alternatively no larva was introduced (control treatment) or larval movement was not confined (free treatment). Three-way interaction between water volume, heterogeneity, and the herbivore significantly affected plant biomass. With a large water volume, plant biomass was lower in free treatment than in control treatment regardless of heterogeneity. Plant biomass in free treatment was as low as in top treatment. With a small water volume and in free treatment, plant biomass was low (similar to that under top treatment) under homogeneous water conditions but high under heterogeneous ones (similar to that under middle or bottom treatment). Therefore, there was little effect of belowground herbivory on plant growth under heterogeneous water conditions. In other watering regimes, herbivores would be distributed in the shallow soil and reduced root biomass. Herbivore mortality was high with homogeneous application of a large volume or heterogeneous application of a small water volume. Under the large water volume, plant biomass was high in pots in which the herbivore had died. Thus, the combinations of water volume and heterogeneity affected plant growth via the change of a belowground herbivore.

  6. First Assessment of Carbon Stock in the Belowground Biomass of Brazilian Mangroves

    Directory of Open Access Journals (Sweden)

    DANIEL M.C. SANTOS

    2017-08-01

    Full Text Available ABSTRACT Studies on belowground roots biomass have increasingly reported the importance of the contribution of this compartment in carbon stock maintenance in mangrove forests. To date, there are no estimates of this contribution in Brazilian mangrove forests, although the country has the second largest area of mangroves worldwide. For this study, trenches dug in fringing forests in Guaratiba State Biological Reserve (Rio de Janeiro, Brazil were used to evaluate the contribution of the different classes of roots and the vertical stratification of carbon stock. The total carbon stock average in belowground roots biomass in these forests was 104.41 ± 20.73 tC.ha−1. From that, an average of 84.13 ± 21.34 tC.ha−1 corresponded to the carbon stock only in fine roots, which have diameters smaller than 5 mm and are responsible for over 80% of the total belowground biomass. Most of the belowground carbon stock is concentrated in the first 40 cm below the surface (about 70%. The root:shoot ratio in this study is 1.14. These estimates demonstrate that the belowground roots biomass significantly contributes, more than 50%, to the carbon stock in mangrove forests. And the mangrove root biomass can be greater than that of other Brazilian ecosystems.

  7. Crop–weed competition

    DEFF Research Database (Denmark)

    Gallandt, Eric R.; Weiner, Jacob

    2015-01-01

    importantly, weed density and time of emergence relative to the crop. Practices that (1) reduce the density of weeds, (2) maximise occupation of space or uptake of resources by the crop or (3) establish an early-season size advantage of the crop over the weeds will minimise the competitive effects of weeds...... an early-season competitive advantage to the crop and (3) maximising resource capture by the crop using competitive species, competitive cultivars, high sowing densities, optimal spatial arrangement, intercropping complimentary species or transplanting.......Competition from weeds is the most important of all biological factors that reduce agricultural crop yield. This occurs primarily because weeds use resources that would otherwise be available to the crop. The magnitude of yield loss is affected by numerous agronomic and environmental factors, most...

  8. Competitiveness through strategic orientation

    Directory of Open Access Journals (Sweden)

    Diego Monferrer

    2012-12-01

    Full Text Available The aim of this paper is to further the study of the factors that influence the international competitive position of international new ventures and, consequently, their international performance. Specifically, we analyze the role of entrepreneurial and market orientations in the international competitive position of such firms. Data were collected at Spanish and Belgian international new ventures. The structural equations model approach was used to test our hypotheses. Both the Spanish and the Belgian sample revealed a positive and significant relationship between entrepreneurial orientation and market orientation. Furthermore, both orientations have a positive and significant effect on the international competitive position of such firms. Finally, any firm’s international competitive position is positively and significantly related to its international performance. The study therefore appears to indicate that, when it comes to international new ventures, the conjunction of these two orientations is a key factor to attaining a superior competitive position and a positive performance in international markets.

  9. Quantifying below-ground nitrogen of legumes: Optimizing procedures for 15N shoot-labelling

    International Nuclear Information System (INIS)

    Khan, D.F.; Peoples, M.B.; Herridge, D.F.

    2003-01-01

    Quantifying below-ground nitrogen (N) of legumes is fundamental to understanding their effects on soil mineral N fertility and on the N economies of following or companion crops in legume-based rotations. Methodologies based on 15 N-labelling of whole plants with subsequent measurement of 15 N in recovered plant parts and in the root-zone soil have proved promising. We report four glasshouse experiments with objectives to develop appropriate protocols for in situ 15 N labelling of four pulses, faba bean (Vicia faba), chickpea (Cicer arietinum), mung bean (Vigna radiata) and pigeon pea (Cajanus cajan). Treatments included 15 N-urea concentration, feeding technique, leaflet/petiole position, and frequency of feeding. Nitrogen- 15 -labelling via the leaf-flap was best for faba bean, mung and pigeon pea, whilst petiole feeding was best for chickpea, in all cases using 0.2-mL volumes of 0.5% urea (98 atom% 15 N excess). The implications of uneven enrichment of the nodulated roots because of effects of the 15 N-depleted nodules when calculating root-derived N in soil are discussed. (author)

  10. The effect of credit rationing on the shape of the competition-innovation relationship

    Czech Academy of Sciences Publication Activity Database

    Bena, Jan

    -, č. 377 (2008), s. 1-48 ISSN 1211-3298 Institutional research plan: CEZ:AV0Z70850503 Keywords : competition * research and development * innovation Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp377.pdf

  11. K-selection, α-selection, effectiveness, and tolerance in competition ...

    Indian Academy of Sciences (India)

    We also use this broader formulation to predict that selection for faster development in Drosophila should, in fact, lead to the correlated evolution of decreased competitive ability, even though it does lead to the evolution of greater efficiency and higher population growth rates at high density when in monotypic culture.

  12. Environmental Management Competitive Pressure Effect on SME Environmental Innovation Activities: A Green Supply Chain Perspective

    Science.gov (United States)

    Rashid, A. A.; Sidek, A. A.; Suffian, S. A.; Daud, M. R. C.

    2018-01-01

    The idea of assimilating green supply chain is to integrate and establish environmental management into the supply chain practices. The study aims to explore how environmental management competitive pressure influences a SME company in Malaysia to incorporate green supply chain integration, which is an efficient platform to develop environmental innovation. This study further advances green supply chain management research in Malaysia by using the method of quantitative analysis to analyze the model developed which data will be collected based on a sample of SMEs in Malaysia in manufacturing sector. The model developed in this study illustrates how environmental management competitive pressure from main competitors affects three fundamental dimensions of green supply chain integration. The research findings suggest that environmental management competitive pressure is a vital driving force for a SME company to incorporate internal and external collaboration in developing green product innovation. From the analysis conducted, the study strongly demonstrated that the best way for a company to counteract competitor’s environmental management success is to first implement strong internal green product development process then move to incorporate external environmental management innovation between their suppliers and customers. The findings also show that internal integration of green product innovation fully mediates the relationship of environmental management competitive pressure and the external integration of green product innovation.

  13. Effects of 7-weeks competitive training period on physiological and mental condition of top level judoists.

    Science.gov (United States)

    Garatachea, N; Hernández-García, R; Villaverde, C; González-Gallego, J; Torres-Luque, G

    2012-02-01

    We examined hormonal and haematological parameters and the profile of mood states (POMS) in top level judoists undertaking a 7-week competitive training period in a real contest. Participants were 10 top level judoists belonging to the Spanish National Team. Training load was calculated by multiplying the training session intensity by the duration of the training session. The judoists competed in two official events on weeks 3 and 6 of the study. Urinary catecholamines increased at the end of the competitive period. Serum cortisol increased during the weeks in which judoists competed, confirming the existence of and anticipatory cortisol response to exercise; although we failed to find serum testosterone increases. Because of leukocyte values did not change, except monocytes, we speculate that the intensity of training was not sufficiently high to evoke injury to muscle tissue. Anger, tension, and fatigue increased according with training load, suggesting that the training exercise led participants into a negative psychological state. Findings indicate that during competitive periods, judoists suffer hormonal and mood changes according to training load and competitive events. Results support the usefulness of monitoring biological and psychological markers during season in order to adjust training loads and periods of recovery.

  14. Effect of phenology on agonistic competitive interactions between invasive and native sheet-web spiders

    Science.gov (United States)

    Houser, Jeremy D.; Porter, Adam H.; Ginsberg, Howard; Jakob, Elizabeth M.

    2016-01-01

    The phenologies of introduced relative to native species can greatly influence the degree and symmetry of competition between them. The European spider Linyphia triangularis (Clerck, 1757) (Linyphiidae) reaches very high densities in coastal Maine (USA). Previous studies suggest thatL. triangularis negatively affects native linyphiid species, with competition for webs as one mechanism. We documented phenological differences between L. triangularis and three native species that illustrate the potential for the reversal of size-based competitive advantage over the course of the year. To test whether relative size influences interaction outcome, we allowed a resident spider to build a web and then introduced an intruder. We examined whether the outcomes of agonistic interactions over the webs were influenced by the species of the resident (invasive or native), the relative size of the contestants, and the species × size interaction. We found that the importance of relative size differed among species. In interactions between L. triangularis and each of two native species, size played a greater role than resident species on the outcome of interactions, suggesting that competitive advantage reverses over the season based on phenology-related size differences. Linyphia triangularis had a negative impact on the third species regardless of relative size.

  15. Distributed energy generation techniques and the competitive fringe effect in electricity markets

    NARCIS (Netherlands)

    Mulder, Machiel; Petrikaite, Vaiva; Scholtens, Bert

    2015-01-01

    We analyse the impact of two different generation techniques used by fringe suppliers on the intensity of competition in the electricity wholesale market. For that purpose, we derive a Cournot model of this market taking into account long-term contracts, international trade and fringe suppliers

  16. Competition effects from cheatgrass (Bromus tectorum) differs among perennial grasses of the Great Basin

    Science.gov (United States)

    Competition from the exotic annual grass, cheatgrass (Bromus tectorum), threatens millions of hectares of native plant communities throughout the Great Basin. The Nature Conservancy has identified the Great Basin as the third most endangered ecosystem in the United States. Not only has increased fue...

  17. Open Competition or Balkanized Coexistence? the Effects of Market Segments on Toronto Private Schools

    Science.gov (United States)

    Pizarro Milian, Roger; Davies, Scott

    2017-01-01

    For over 25 years, school choice advocates have argued that market competition drives educational organizations to become more differentiated and technically-oriented. However, empirical research has only partially supported this view, observing such outcomes only under certain conditions. To better understand the contingent nature of market…

  18. Competition and wage effects in the global online market for microwork and services outsourcing

    NARCIS (Netherlands)

    Beerepoot, N.; Lambregts, B.; Nicholson, B.; Babin, R.; Lacity, M.C.

    2016-01-01

    A new form of service outsourcing has emerged, namely the global online job marketplace for freelance contractors. Such platforms are currently the closest proxy to the idea of a global labor market. In this chapter, we examine how competition manifests itself on one such global online platform,

  19. The Effect of Salts in Promoting Specific and Competitive Interactions between Zinc Finger Proteins and Metals

    Science.gov (United States)

    Li, Gongyu; Yuan, Siming; Zheng, Shihui; Chen, Yuting; Zheng, Zhen; Liu, Yangzhong; Huang, Guangming

    2017-12-01

    Specific protein-metal interactions (PMIs) fulfill essential functions in cells and organic bodies, and activation of these functions in vivo are mostly modulated by the complex environmental factors, including pH value, small biomolecules, and salts. Specifically, the role of salts in promoting specific PMIs and their competition among various metals has remained untapped mainly due to the difficulty to distinguish nonspecific PMIs from specific PMIs by classic spectroscopic techniques. Herein, we report Hofmeister salts differentially promote the specific PMIs by combining nanoelectrospray ionization mass spectrometry and spectroscopic techniques (fluorescence measurement and circular dichroism). Furthermore, to explore the influence of salts in competitive binding between metalloproteins and various metals, we designed a series of competitive experiments and applied to a well-defined model system, the competitive binding of zinc (II) and arsenic (III) to holo-promyelocytic leukemia protein (PML). These experiments not only provided new insights at the molecular scale as complementary to previous NMR and spectroscopic results, but also deduced the relative binding ability between zinc finger proteins and metals at the molecular scale, which avoids the mass spectrometric titration-based determination of binding constants that is frequently affected and often degraded by variable solution conditions including salt contents. [Figure not available: see fulltext.

  20. Price Competition in Weapons Production: A Framework to Analyze its Cost-Effectiveness

    Science.gov (United States)

    1984-06-01

    development, test, and eva luat ion (RI) I ,E ) expend i tu res on a jaor p rogram is h iq. or e amp I t a; shown in Tahle 1, CoI;irn -4, the est imated base...R. Hiller , Predicting the Cost and Benefits of Competitive Production Sources, Report R--5--lrl ington, Va.: The Analytic Sciences Corporation

  1. Exploring the Effects of Contest Mechanisms on Idea Shortlisting in an Open Idea Competition

    DEFF Research Database (Denmark)

    Merz, Alexander Benedikt; Seeber, Isabella; Maier, Ronald

    2016-01-01

    Picking the most promising from a multitude of crowd-generated ideas challenges organizations that employ open idea competitions. Hence, hosts of such contests often filter submitted ideas into shortlists to help juries selecting the winning ideas. While contest communities and rewards have been...

  2. The effect of competition on process and outcome quality within hospital care in The Netherlands

    NARCIS (Netherlands)

    Bijlsma, M.; Koning, P.W.C.; Shestalova, V.

    2011-01-01

    This study examines the impact of competition on hospital quality. Our panel covers all Dutch hospitals in the period 2004–2008, in which the transparency of hospital quality information increased substantially. The paper contributes to the existing literature by including both outcome and process

  3. in_focus - Competition and Development: The Power of Competitive ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2008-01-01

    Jan 1, 2008 ... This book demonstrates the importance of true and fair competition to sustainable development and an effective marketplace, touching on issues of globalization, consumer welfare, cartels and monopolies, and trade liberalization. It provides an introduction to competition, and competition law and policy in ...

  4. Evidence that acidification-induced declines in plant diversity and productivity are mediated by changes in below-ground communities and soil properties in a semi-arid steppe

    Science.gov (United States)

    Chen, Dima; Lan, Zhichun; Bai, Xue; Grace, James B.; Bai, Yongfei

    2013-01-01

    Anthropogenic acid deposition–induced soil acidification is one of the major threats to biodiversity, ecosystem functioning and services. Few studies, however, have explored in detail how above-ground changes in plant species richness and productivity resulting from soil acidification are mediated by effects on below-ground biota and soil properties.

  5. Prediction of the competitive effects of weeds on crop yields based on the relative leaf area of weeds

    DEFF Research Database (Denmark)

    Lotz, L. A. P.; Christensen, Svend; Cloutier, D.

    1996-01-01

    L.) and in 11 experiments in spring wheat (Triticum aestivum L.). Most data sets were heller described by a model based on the relative leaf area of the weed than by a hyperbolic model based on weed density. This leaf area model accounted for (part of) the effect of different emerging times of the S....... alba whereas the density model did not. A parameter that allows the maximum yield loss to be smaller than 100% was mostly not needed to describe the effects of weed competition. The parameter that denotes the competitiveness of the weed species with respect to the crop decreased the later the relative...... leaf area of the mustard was determined. This decrease could be estimated from the differences in relative growth rate of the leaf area of crop and S. alba. However, the accuracy of this estimation was poor. The parameter value of the leaf area model varied considerably between sites and years...

  6. Competitive effects and instruments of power sector reforms. International reform concepts blockade structures, risk distribution. A political economy analysis

    International Nuclear Information System (INIS)

    Liebchen, Armin

    2014-01-01

    Power sectors with weak or inadequate competition structures are the rule, despite numerous attempts at reform. But can afford modern economies this defect for a long time? Why can the implementation of competition are blocked so effectively? The author studied international reform experiences and opens up interesting insights that can also reflect on problems of the German energy turnaround: The difficulty of timing and coordination of the reform components, the development of resistance levels of individual interest groups, breach of contract as a rational alternative, causes unwanted price effects, shifting interest situations of major stakeholders, change dynamics impending regulatory risks, pending financing risks, stranded cost-conflict situations for power stations disconnected from the grid and facilities and instruments of a political and regulatory risk management for reforms. With numerous examples, background analyzes and instruments to reform analysis, this book is aimed at investors, policy planners and analysts. [de

  7. Coal competitiveness?

    International Nuclear Information System (INIS)

    Rogeaux, B.

    2006-01-01

    Will coal electrical plants be more competitive in the coming years? Answering this one cannot be limited to merely comparing estimates based on reference electricity production costs. The competitiveness of coal will indeed depend on the final product marketed, as the MWhs are not equal: is the purpose to produce base, half-base MWh? Does the electrical equipment structure require flexible MWh (for instance in the event of significant intermittent renewable energy amounts), and therefore plants able to adjust their power rapidly? But the competitiveness of coal will also depend on many factors that will correct reference cost estimates: uncertainties, risks, externalities. These factors will need to be appreciated on a case by case basis. We introduce some of the reasoning used to better appreciate the future competitiveness of coal, and the main factors conditioning it in three contrasting regions of the world: Europe, USA, china. (author)

  8. Effect of competitiveness on forty-yard dash performance in college men and women.

    Science.gov (United States)

    Moore, Ashley N; Decker, Aaron J; Baarts, Jennifer N; Dupont, Andrea M; Epema, John S; Reuther, Michael C; Houser, Jeremy J; Mayhew, Jerry L

    2007-05-01

    The objective of this study was to determine performance differences between individual and competitive trials of the 40-yard dash. Physically active college men (n = 25) and women (n = 29) performed an individual 40-yard dash, followed by completion of the Sports Competition Trait Inventory (SCTI) before performing a paired 40-yard dash against a time-matched competitor. All sprints were performed on an indoor rubberized track using photoelectric gates to start and stop a digital timer. In addition, 3 timers used hand-held stopwatches to record the individual sprint time. There was no significant difference (p = 0.10) between men (120.3 +/- 16.6) and women (111.7 +/- 20.3) on the SCTI. There was no significant difference between individual and competitive 40-yard dash times for either men (5.21 +/- 0.24 and 5.19 +/- 0.23 seconds, respectively) or women (6.12 +/- 0.31 and 6.11 +/- 0.32 seconds, respectively). The correlation between SCTI and both individual and competitive 40-yard dashes was significant (p < 0.05) for women (r = -0.45 and -0.44, respectively) but not for men (r = -0.10 and 0.10, respectively). Electronic times (5.70 +/- 0.54 seconds) were not significantly different from 1 hand-timer (5.71 +/- 0.56 seconds) but were significantly faster than the other 2 timers (5.80 +/- 0.58 and 5.82 +/- 0.57 seconds). Averaging the 3 hand times (5.78 +/- 0.56 seconds) for comparison with the electronic timing (5.70 +/- 0.54 seconds) produced a high correlation (r = 0.96) but a significantly slower time (p < 0.05). A competitive environment does not appear to improve short sprint times in either men or women. In addition, hand timing may not always produce faster times compared to electronic timing.

  9. Understanding competitiveness

    OpenAIRE

    CRESPO, Aranzazu; SEGURA-CAYUELA, Ruben

    2014-01-01

    Using firm level data, we analyze the factors that drive the evolution of the aggregate Unit Labor Costs – the main European competitiveness indicator – in France, Germany, Italy and Spain. The evolution of the aggregate Unit Labor Cost is not driven by the evolution of the firm level Unit Labor Costs, but rather by an important factor for the competitiveness of a country: the reallocation of resources among the firms of the economy. Using the methodology of Hsieh and Klenow (...

  10. REGIONAL COMPETITIVENESS

    OpenAIRE

    Krželj-Čolović, Zorica

    2015-01-01

    Individual city and regional authorities in many countries have themselves taken up the issue of “competitiveness” as part of their own economic development agendas: competitiveness has come to be regarded as critical for understanding and promoting local economic performance. Like their national counterparts, regional and city policy-makers have become preoccupied with knowing the relative competitive standing of their local economies compared with others, not just other regions and cities w...

  11. The effect of recovery strategies on physical performance and cumulative fatigue in competitive basketball.

    Science.gov (United States)

    Montgomery, Paul G; Pyne, David B; Hopkins, Will G; Dorman, Jason C; Cook, Katherine; Minahan, Clare L

    2008-09-01

    To evaluate the effectiveness of recovery strategies on physical performance during a 3-day tournament style basketball competition, 29 male players (mean age 19.1 years, s= 2.1; height 1.84 m, s= 0.34; body mass 88.5 kg, s= 14.7) were assigned to one of three treatment groups: carbohydrate+stretching (7.7 g kg(-1) day(-1), s= 1.7; 'n = 9), cold water immersion (11 degrees C, 5 x 1; n = 10) or full leg compression garments (18 mmHg, approximately 18 h; n = 10). Effects of the recovery strategies on pre-post tournament performance tests were expressed as the mean change (% +/- standard deviation of the change score). Changes and differences were standardized for accumulated game time, assessed against the smallest worthwhile change for each test, and reported qualitatively. Accumulated fatigue was evident over the tournament with small to moderate impairments in performance tests. Sprint and agility performance decreased by 0.7% (s = 1.3) and 2.0% (s = 1.9) respectively. Vertical jump decreased substantially after the first day for all treatments, and remained suppressed post-tournament. Cold water immersion was substantially better in maintaining 20-m acceleration with only a 0.5% (s = 1.4) reduction in 20-m time after 3 days compared with a 3.2% (s = 1.6) reduction for compression. Cold water immersion (-1.4%, s = 1.7) and compression (-1.5%, s = 1.7) showed similar substantial benefits in maintaining line-drill performance over the tournament, whereas carbohydrate+stretching elicited a 0.4% (s =1.8) reduction. Sit-and-reach flexibility decreased for all groups, although cold water immersion resulted in the smallest reduction in flexibility. Basketball tournament play elicited small to moderate impairments in physical test performance. In conclusion, cold water immersion appears to promote better restoration of physical performance measures than carbohydrate + stretching routines and compression garments.

  12. Initial success of native grasses is contingent on multiple interactions among exotic grass competition, temporal priority, rainfall and site effects.

    Science.gov (United States)

    Young, Truman P; Zefferman, Emily P; Vaughn, Kurt J; Fick, Stephen

    2014-12-05

    Ecological communities are increasingly being recognized as the products of contemporary drivers and historical legacies that are both biotic and abiotic. In an attempt to unravel multiple layers of ecological contingency, we manipulated (i) competition with exotic annual grasses, (ii) the timing of this competition (temporal priority in arrival/seeding times) and (iii) watering (simulated rainfall) in a restoration-style planting of native perennial grasses. In addition, we replicated this experiment simultaneously at three sites in north-central California. Native perennial grasses had 73-99 % less cover when planted with exotic annuals than when planted alone, but this reduction was greatly ameliorated by planting the natives 2 weeks prior to the exotics. In a drought year, irrigation significantly reduced benefits of early planting so that these benefits resembled those observed in a non-drought year. There were significant differences across the three sites (site effects and interactions) in (i) overall native cover, (ii) the response of natives to competition, (iii) the strength of the temporal priority effect and (iv) the degree to which supplemental watering reduced priority effects. These results reveal the strong multi-layered contingency that underlies even relatively simple communities. Published by Oxford University Press on behalf of the Annals of Botany Company.

  13. Soil fertility shapes belowground food webs across a regional climate gradient.

    Science.gov (United States)

    Laliberté, Etienne; Kardol, Paul; Didham, Raphael K; Teste, François P; Turner, Benjamin L; Wardle, David A

    2017-10-01

    Changes in soil fertility during pedogenesis affect the quantity and quality of resources entering the belowground subsystem. Climate governs pedogenesis, yet how climate modulates responses of soil food webs to soil ageing remains unexplored because of the paucity of appropriate model systems. We characterised soil food webs along each of four retrogressive soil chronosequences situated across a strong regional climate gradient to show that belowground communities are predominantly shaped by changes in fertility rather than climate. Basal consumers showed hump-shaped responses to soil ageing, which were propagated to higher-order consumers. There was a shift in dominance from bacterial to fungal energy channels with increasing soil age, while the root energy channel was most important in intermediate-aged soils. Our study highlights the overarching importance of soil fertility in regulating soil food webs, and indicates that belowground food webs will respond more strongly to shifts in soil resources than climate change. © 2017 John Wiley & Sons Ltd/CNRS.

  14. Aboveground endophyte affects root volatile emission and host plant selection of a belowground insect.

    Science.gov (United States)

    Rostás, Michael; Cripps, Michael G; Silcock, Patrick

    2015-02-01

    Plants emit specific blends of volatile organic compounds (VOCs) that serve as multitrophic, multifunctional signals. Fungi colonizing aboveground (AG) or belowground (BG) plant structures can modify VOC patterns, thereby altering the information content for AG insects. Whether AG microbes affect the emission of root volatiles and thus influence soil insect behaviour is unknown. The endophytic fungus Neotyphodium uncinatum colonizes the aerial parts of the grass hybrid Festuca pratensis × Lolium perenne and is responsible for the presence of insect-toxic loline alkaloids in shoots and roots. We investigated whether endophyte symbiosis had an effect on the volatile emission of grass roots and if the root herbivore Costelytra zealandica was able to recognize endophyte-infected plants by olfaction. In BG olfactometer assays, larvae of C. zealandica were more strongly attracted to roots of uninfected than endophyte-harbouring grasses. Combined gas chromatography-mass spectrometry and proton transfer reaction-mass spectrometry revealed that endophyte-infected roots emitted less VOCs and more CO2. Our results demonstrate that symbiotic fungi in plants may influence soil insect distribution by changing their behaviour towards root volatiles. The well-known defensive mutualism between grasses and Neotyphodium endophytes could thus go beyond bioactive alkaloids and also confer protection by being chemically less apparent for soil herbivores.

  15. Competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons: effects of edge-functionalization.

    Science.gov (United States)

    Lu, Xiaoqing; Jin, Dongliang; Wei, Shuxian; Zhang, Mingmin; Zhu, Qing; Shi, Xiaofan; Deng, Zhigang; Guo, Wenyue; Shen, Wenzhong

    2015-01-21

    The effect of edge-functionalization on the competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons (NPCs) has been investigated for the first time by combining density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation. Our results show that edge-functionalization has a more positive effect on the single-component adsorption of CO2 than CH4, therefore significantly enhancing the selectivity of CO2 over CH4, in the order of NH2-NPC > COOH-NPC > OH-NPC > H-NPC > NPC at low pressure. The enhanced adsorption originates essentially from the effects of (1) the conducive environment with a large pore size and an effective accessible surface area, (2) the high electronegativity/electropositivity, (3) the strong adsorption energy, and (4) the large electrostatic contribution, due to the inductive effect/direct interaction of the embedded edge-functionalized groups. The larger difference from these effects results in the higher competitive adsorption advantage of CO2 in the binary CO2-CH4 mixture. Temperature has a negative effect on the gas adsorption, but no obvious influence on the electrostatic contribution on selectivity. With the increase of pressure, the selectivity of CO2 over CH4 first decreases sharply and subsequently flattens out to a constant value. This work highlights the potential of edge-functionalized NPCs in competitive adsorption, capture, and separation for the binary CO2-CH4 mixture, and provides an effective and superior alternative strategy in the design and screening of adsorbent materials for carbon capture and storage.

  16. An experimental analysis of spatial competition in a dense infaunal community: The importance of relative effects

    Science.gov (United States)

    Wilson, W. Herbert

    1984-06-01

    A densely populated soft-sediment community was experimentally analysed for interspecific competition for space in laboratory experiments. No interspecific competitive interactions leading to a decrease in survivorship could be documented over a five-week period. The four most abundant species all coexisted in laboratory microcosms. The two tube-buiding species, the tanaid Leptochelia dubia and the polychaete Rhynchospio arenincola, could not exclude the mobile bivalve Transennella tantilla or the burrowing amphipod Paraphoxus spinosus. None of the species increases its emigration frequency when other species are present. Paraphoxus is found to be a browsing predator on Phynchospio but inflicts no detectable mortality. The coexistence of these species is permitted by virtue of the fact that none of the species can alter the soft-sediment habitat sufficiently to make the habitat unsuitable for the other species.

  17. Effects of competition and cooperation interaction between agents on networks in the presence of a market capacity

    Science.gov (United States)

    Sonubi, A.; Arcagni, A.; Stefani, S.; Ausloos, M.

    2016-08-01

    A network effect is introduced taking into account competition, cooperation, and mixed-type interaction among agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity undoubtedly enforces a definite limit on the agent's size growth. The state stability of triadic agents, i.e., the most basic network plaquette, is investigated analytically for possible scenarios, through a fixed-point analysis. It is discovered that: (i) market demand is only satisfied for full competition when one agent monopolizes the market; (ii) growth of agent size is encouraged in full cooperation; (iii) collaboration among agents to compete against one single agent may result in the disappearance of this single agent out of the market; and (iv) cooperating with two rivals may become a growth strategy for an intelligent agent.

  18. The effect of environmental regulation on firms' competitive performance: the case of the building & construction sector in some EU regions.

    Science.gov (United States)

    Testa, Francesco; Iraldo, Fabio; Frey, Marco

    2011-09-01

    There is a considerable debate on the effects of environmental regulation on competitive performance. Based on survey data, this paper analyzes the two main research questions, derived from literature, on the links between environmental regulation and competitiveness, by focusing on firms operating in the building and construction sector, i.e.: 1) whether environmental policy stringency affects the competitive performance of firms in the building and construction sector 2) and how a specific form of environmental regulation (direct regulation, economic instruments and soft instruments) affects this performance? By applying a regression analysis, we find that a more stringent environmental regulation, measured by inspection frequency, provides a positive impulse for increasing investments in advanced technological equipment and innovative products and on business performance. Moreover, a well-designed "direct regulation" appears to be the most effective policy instrument for prompting the positive impact of environmental policies on innovation and intangible performance while economic instruments do negatively affect business performance. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Coexistence via coevolution driven by reduced allelochemical effects and increased tolerance to competition between invasive and native plants.

    Science.gov (United States)

    Huang, Fangfang; Lankau, Richard; Peng, Shaolin

    2018-04-01

    Coevolution can promote long-term coexistence of two competing species if selection acts to reduce the fitness inequality between competitors and/or strengthen negative frequency dependence within each population. However, clear coevolution between plant competitors has been rarely documented. Plant invasions offer opportunities to capture the process of coevolution. Here we investigated how the developing relationship between an invasive forb, Alliaria petiolata, and a native competitor, Pilea pumila, may affect their long-term coexistence, by testing the competitive effects of populations of varying lengths of co-occurrence on each other across a chronosequence of invasion history. Alliaria petiolata and P. pumila tended to develop greater tolerance to competition over invasion history. Their coexistence was promoted more by increases in stabilizing relative to equalizing processes. These changes likely stem in part from reductions in allelopathic traits in the invader and evolution of tolerance in the native. These results suggested that some native species can evolve tolerance against the competitive effects of strong invaders, which likely promoted their persistence in invaded communities. However, the potential for coevolutionary rescue of competing populations is likely to vary across native species, and evolutionary processes should not be expected to compensate for the ecological consequences of exotic invasions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  20. Temporal analysis of national level Muay-Thai matches: Effects of competitive phase

    Directory of Open Access Journals (Sweden)

    Fabrício Boscolo Del Vecchio

    2015-06-01

    Full Text Available Introduction: Temporal analysis of matches allows the study of fighting patterns in combat sports. With this procedure, we can recreate the efforts in specific training. However, up to date have no information concerning temporal analysis considering competitive level in Muay-Thai. Objective: To investigate temporal characteristics of Muay-Thai athletes in official competition from national level, considering round, and to compare preliminary combats with those that had medal disputes. Material and methods: Were recorded 65 matches in a Brazilian championship. We conducted in loco recording. To time-motion analysis, Software Kinovea™ was used. Were considered Observation, Preparation and Interaction periods, as well as high intensity and low intensity ratio (HI:LI. The average duration of the rounds between competitive phases (preliminary or finals was compared with a t test. A generalized linear model was applied considering effort duration as dependent variable and competitive level, round and effort type as independent. Significant level was set in 5%. Results: Were registered 7 to 8 s of Observation, near from 3 s of Preparation and 4 to 5.5 s of Interaction effort type, and the duration of Observation effort was significantly superior the others. Significant differences were observed in the Interaction between preliminary and finals (respectively 5.5 ± 0.3 s and 3.7 ± 0.5 s; p < 0.05. Pooling the Observation and Preparation time as low intensity (LI, and Interaction as high intensity (HI efforts, the HI:LI ratio was 1:2in eliminatory and 1:3 in the final matches. Conclusions: Muay-Thai is an intermittent combat sport, the duration of Interaction effort type is lower in final in comparison to preliminary matches.

  1. Increased stem density and competition may diminish the positive effects of warming at alpine treeline

    OpenAIRE

    Wang, Yafeng; Pederson, Neil; Ellison, Aaron M.; Buckley, Hannah L.; Case, Bradley; Liang, Eryuan; Camarero, J Julio

    2016-01-01

    The most widespread response to global warming among alpine treeline ecotones is not an upward shift, but an increase in tree density. However, the impact of increasing density on interactions among trees at treeline is not well understood. Here, we test if treeline densification induced by climatic warming leads to increasing intraspecific competition. We mapped and measured the size and age of Smith fir trees growing in two treelines located in the southeastern Tibetan Plateau. We used spat...

  2. Essays on the Competitive Effects of Disaster in Electrical Power Markets

    OpenAIRE

    O'Fallon, Cheyney Michael Thomas

    2016-01-01

    Competition in the generation and marketing of electricity entails the use of a strategy space with many dimensions. Often requiring outlays in the hundreds of millions and occasionally billions of dollars to build, power plants are infrastructure investments with huge potential for economic impact. A variety of generating technologies currently compete to be the lowest cost provider and each of these options includes a set of externalities associated with producing power. Therefore, some ...

  3. The effect of competition on nursing home expenditures under prospective reimbursement.

    OpenAIRE

    Nyman, J A

    1988-01-01

    The for-profit nursing home's incentive to minimize costs has been maligned as a major cause of the quality problems that have traditionally plagued the nursing home care industry. Yet, profit-maximizing firms in other industries are able to produce products of adequate quality. In most other industries, however, firms are constrained from reducing costs to the point where quality suffers by the threat of losing business to competing firms. In the nursing home industry, competition for patien...

  4. Effects of combination of leaf resources on competition in container mosquito larvae

    OpenAIRE

    Reiskind, M.H.; Zarrabi, A.A.; Lounibos, L.P.

    2012-01-01

    Resource diversity is critical to fitness in many insect species, and may determine the coexistence of competitive species and the function of ecosystems. Plant material provides the nutritional base for numerous aquatic systems, yet the consequences of diversity of plant material have not been studied in aquatic container systems important for the production of mosquitoes. To address how diversity in leaf detritus affects container-inhabiting mosquitoes, we examined how leaf species affect c...

  5. The effects of press variations in competitive athletes on muscle activity and performance

    OpenAIRE

    Sæterbakken, Atle Hole; Mo, Dag André; Scott, Suzanne; Andersen, Vidar

    2017-01-01

    Abstract The aim of the study was to compare the EMG activity performing 6RM competition style bench press (flat bench-wide grip) with 1) medium and narrow grip widths on a flat bench and 1) inclined and declined bench positions with a wide grip. Twelve bench press athletes competing at national and international level participated in the study. EMG activity was measured in the pectoralis major, anterior and posterior deltoid, biceps brachii, triceps brachii and latissimus dorsi. Non-signific...

  6. Phenology of perennial native grass below-ground axillary buds in the northern mixed-grass prairie

    Science.gov (United States)

    Vegetative reproduction from belowground bud banks is the primary driver of grassland systems. Despite the importance of vegetative reproduction, the timing of belowground bud recruitment is unknown for most dominant, perennial native grasses as is the relationship between bud development and envir...

  7. Belowground interactions with aboveground consequences: Invasive earthworms and arbuscular mycorrhizal fungi.

    Science.gov (United States)

    Paudel, Shishir; Longcore, Travis; MacDonald, Beau; McCormick, Melissa K; Szlavecz, Katalin; Wilson, Gail W T; Loss, Scot R

    2016-03-01

    A mounting body of research suggests that invasive nonnative earthworms substantially alter microbial communities, including arbuscular mycorrhizal fungi (AMF). These changes to AMF can cascade to affect plant communities and vertebrate populations. Despite these research advances, relatively little is known about (1) the mechanisms behind earthworms' effects on AMF and (2) the factors that determine the outcomes of earthworm-AMF interactions (i.e., whether AMF abundance is increased or decreased and subsequent effects on plants). We predict that AMF-mediated effects of nonnative earthworms on ecosystems are nearly universal because (1) AMF are important components of most terrestrial ecosystems, (2) nonnative earthworms have become established in nearly every type of terrestrial ecosystem, and (3) nonnative earthworms, due to their burrowing and feeding behavior, greatly affect AMF with potentially profound concomitant effects on plant communities. We highlight the multiple direct and indirect effects of nonnative earthworms on plants and review what is currently known about the interaction between earthworms and AMF. We also illustrate how the effects of nonnative earthworms on plant-AMF mutualisms can alter the structure and stability of aboveground plant communities, as well as the vertebrate communities relying on these habitats. Integrative studies that assess the interactive effects of earthworms and AMF can provide new insights into the role that belowground ecosystem engineers play in altering aboveground ecological processes. Understanding these processes may improve our ability to predict the structure of plant and animal communities in earthworm-invaded regions and to develop management strategies that limit the numerous undesired impacts of earthworms.

  8. Effects of local adaptation and interspecific competition on species' responses to climate change.

    Science.gov (United States)

    Bocedi, Greta; Atkins, Katherine E; Liao, Jishan; Henry, Roslyn C; Travis, Justin M J; Hellmann, Jessica J

    2013-09-01

    Local adaptation and species interactions have been shown to affect geographic ranges; therefore, we need models of climate impact that include both factors. To identify possible dynamics of species when including these factors, we ran simulations of two competing species using an individual-based, coupled map-lattice model using a linear climatic gradient that varies across latitude and is warmed over time. Reproductive success is governed by an individual's adaptation to local climate as well as its location relative to global constraints. In exploratory experiments varying the strength of adaptation and competition, competition reduces genetic diversity and slows range change, although the two species can coexist in the absence of climate change and shift in the absence of competitors. We also found that one species can drive the other to extinction, sometimes long after climate change ends. Weak selection on local adaptation and poor dispersal ability also caused surfing of cooler-adapted phenotypes from the expanding margin backwards, causing loss of warmer-adapted phenotypes. Finally, geographic ranges can become disjointed, losing centrally-adapted genotypes. These initial results suggest that the interplay between local adaptation and interspecific competition can significantly influence species' responses to climate change, in a way that demands future research. © 2013 New York Academy of Sciences.

  9. The effect of virus-blocking Wolbachia on male competitiveness of the dengue vector mosquito, Aedes aegypti.

    Science.gov (United States)

    Segoli, Michal; Hoffmann, Ary A; Lloyd, Jane; Omodei, Gavin J; Ritchie, Scott A

    2014-12-01

    The bacterial endosymbiont Wolbachia blocks the transmission of dengue virus by its vector mosquito Aedes aegypti, and is currently being evaluated for control of dengue outbreaks. Wolbachia induces cytoplasmic incompatibility (CI) that results in the developmental failure of offspring in the cross between Wolbachia-infected males and uninfected females. This increases the relative success of infected females in the population, thereby enhancing the spread of the beneficial bacterium. However, Wolbachia spread via CI will only be feasible if infected males are sufficiently competitive in obtaining a mate under field conditions. We tested the effect of Wolbachia on the competitiveness of A. aegypti males under semi-field conditions. In a series of experiments we exposed uninfected females to Wolbachia-infected and uninfected males simultaneously. We scored the competitiveness of infected males according to the proportion of females producing non-viable eggs due to incompatibility. We found that infected males were equally successful to uninfected males in securing a mate within experimental tents and semi-field cages. This was true for males infected by the benign wMel Wolbachia strain, but also for males infected by the virulent wMelPop (popcorn) strain. By manipulating male size we found that larger males had a higher success than smaller underfed males in the semi-field cages, regardless of their infection status. The results indicate that Wolbachia infection does not reduce the competitiveness of A. aegypti males. Moreover, the body size effect suggests a potential advantage for lab-reared Wolbachia-males during a field release episode, due to their better nutrition and larger size. This may promote Wolbachia spread via CI in wild mosquito populations and underscores its potential use for disease control.

  10. A Randomized Controlled Trial to Assess the Effects of Competition on the Development of Laparoscopic Surgical Skills.

    Science.gov (United States)

    Hashimoto, Daniel A; Gomez, Ernest D; Beyer-Berjot, Laura; Khajuria, Ankur; Williams, Noel N; Darzi, Ara; Aggarwal, Rajesh

    2015-01-01

    Serious games have demonstrated efficacy in improving participation in surgical training activities, but studies have not yet demonstrated the effect of serious gaming on performance. This study investigated whether competitive training (CT) affects laparoscopic surgical performance. A total of 20 novices were recruited, and 18 (2 dropouts) were randomized into control or CT groups to perform 10 virtual reality laparoscopic cholecystectomies (LCs). Competitiveness of each participant was assessed. The CT group members were informed they were competing to outperform one another for a prize; performance ranking was shown before each session. The control group did not compete. Performance was assessed on time, movements, and instrument path length. Quality of performance was assessed with a global rating scale score. There were no significant intergroup differences in baseline skill or measured competitiveness. Time and global rating scale score, at final LC, were not significantly different between groups; however, the CT group was significantly more dexterous than control and had significantly lower variance in number of movements and instrument path length at the final LC (p = 0.019). Contentiousness was inversely related to time in the CT group. This was the first randomized controlled trial to investigate if CT can enhance performance in laparoscopic surgery. CT may lead to improved dexterity in laparoscopic surgery but yields otherwise similar performance to that of standard training in novices. Competition may have different effects on novices vs experienced surgeons, and subsequent research should investigate CT in experienced surgeons as well. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  11. CONCEPTUAL APPROACH OF COMPETITIVENESS AND INTERDEPENDENCE BETWEEN COMPETITION AND COMPETITIVENESS

    Directory of Open Access Journals (Sweden)

    Tatiana GUTIUM

    2017-11-01

    Full Text Available This article is devoted to analysis of interdependence and correlation between competition and competitiveness, and competition’s consequences. The author analysed some authors’ visions on competitiveness, and common features between theories of competition and competitiveness. Using the synthetic indicator elaborated by author has been evaluated the competitiveness of domestic goods on the internal and external market. At the end of this article, the author has developed proposals to increase competitiveness.

  12. Belowground biotic complexity drives aboveground dynamics: a test of the soil community feedback model.

    Science.gov (United States)

    Pendergast, Thomas H; Burke, David J; Carson, Walter P

    2013-03-01

    Feedbacks between soil communities and plants may determine abundance and diversity in plant communities by influencing fitness and competitive outcomes. We tested the core hypotheses of soil community feedback theory: plant species culture distinct soil communities that alter plant performance and the outcome of interspecific competition. We applied this framework to inform the repeated dominance of Solidago canadensis in old-field communities. In glasshouse experiments, we examined the effects of soil communities on four plant species' performance in monoculture and outcomes of interspecific competition. We used terminal restriction fragment length polymorphism (TRFLP) analysis to infer differences in the soil communities associated with these plant species. Soil community origin had strong effects on plant performance, changed the intensity of interspecific competition and even reversed whether plant species were limited by conspecifics or heterospecifics. These plant-soil feedbacks are strong enough to upend winners and losers in classic competition models. Plant species cultured significantly different mycorrhizal fungal and bacterial soil communities, indicating that these feedbacks are likely microbiotic in nature. In old-fields and other plant communities, these soil feedbacks appear common, fundamentally alter the intensity and nature of plant competition and potentially maintain diversity while facilitating the dominance of So. canadensis. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  13. Subcontract Competition.

    Science.gov (United States)

    1982-11-01

    DRCPM- ROL USA Missile Command, ATTN: DRCPM-VI Armor Training Devices, ATTN: DRCPM-AR 3 APRO 82-11 FINAL SUBCONTRACT COMPETITION by Wayne V. Zabel Charles...A. Correia "I S The pronouns "he," "his," and "him," when used in this publication, represent both the masculine and feminine genders unless... advertising or by negotiation, shall be made on a competitive basis to the maximum practicable extent." Armed Services Procurement Regul-tion Manual

  14. Comparing the effect of short-term detraining on athletic performance of elite competitive children and adolescent swimmers

    Directory of Open Access Journals (Sweden)

    Parisa Sedaghati

    2018-04-01

    Full Text Available Background: Optimum functioning of the competitive swimmers depends on the adaptations in power and strength of superficial, upper and lower limbs and interaction with core stabilizing muscles of the body. The aim of this study was to compare the effect of short periods of detraining on exercise performance of elite competitive children and adolescents swimmers. Materials and Methods: In this prospective cohort study, 48 female participants with a history of more than 2 years (Damash Team of professional exercise at Alborz province were selected based on available sampling and were assigned into 2 equal groups of children and adolescents based on their age. During the two periods, dependent variables, endurance of the trunk flexors, lateralis and flexors of the trunk, strength of the trunk muscles, dynamic balance and the performance of the swimmers (50 and 100 m were evaluated. Results: Comparison of the results for swimming speed (50 m showed a significant difference between the adolescent and children groups (P=0.001. In addition, total endurance of trunk muscles, power of trunk muscles and the dynamic balance in adolescents showed a significant difference (P=0.01, but the dynamic balance and swimming speed (50 and 100 m were significant only in the children group (P=0.001. Conclusion: A 25-day detraining period results in a considerable alteration in the trunk muscle function, balance, and exercise performance of the competitive swimmers, especially among the children.

  15. Combined effects of temperature and interspecific competition on the mortality of the invasive garden ant, Lasius neglectus: A laboratory study.

    Science.gov (United States)

    Frizzi, Filippo; Bartalesi, Viola; Santini, Giacomo

    2017-04-01

    The invasive garden ant, Lasius neglectus, is a dominant species due to its capacity to form large supercolonies. This species was assumed to possess a wide thermal niche since it is able to adapt to cold climates, which is a factor that boosted its rapid expansion from south to many central-northern European Countries. However, the effect of variations in environmental temperatures on its competitive ability against other species has still not been investigated. In this paper, we analyzed the change in survival ability of Lasius neglectus during encounters with two Mediterranean dominant ants (Crematogaster scutellaris and Tapinoma nigerrimum) at four different temperatures (15, 20, 25 and 30°C). Firstly, control tests were performed to provide the baseline survival ability of the three species at different temperatures. Secondly, competition tests were carried out at the same temperatures. Lasius neglectus survival was negatively affected by high temperature (30°C) in control tests, and this impairment was much more pronounced in competition tests. On the contrary, the two opponent species were only marginally affected by temperatures in control tests. Crematogaster scutellaris was a better competitor than L. neglectus, particularly at high temperatures. Tapinoma nigerrimum was a weaker competitor and was always outcompeted by L. neglectus, particularly at low temperatures. This result could suggest that L. neglectus is at a disadvantage during interspecific encounters when temperatures are high and that the predicted future increase in environmental temperatures may potentially enhance this handicap. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The effects of adult sex ratio on mating competition in male and female guppies (Poecilia reticulata) in two wild populations.

    Science.gov (United States)

    Chuard, Pierre J C; Brown, Grant E; Grant, James W A

    2016-08-01

    When competing for mates, males typically exhibit higher rates of intrasexual aggression and courtship than females. Operational sex ratio, represented here by adult sex ratio (ASR) as a proxy, is likely the best predictor of this competition, which typically increases between members of one sex as members of the opposite sex become rarer. Moreover, in populations subject to high predation, males often decrease mating competitive behaviour due to predation risk. We explored the combined effects of ASR and population of origin (low vs. high ambient predation risk) on mating competition in male and female wild-caught Trinidadian guppies. Both male and female aggression rates increased with ASR, but the increase for males was only significant in the low-predation population. In regard to male mating tactics, courtship propensity was unaffected by ASR, while the propensity to sneak increased at male-biased ASRs. Guppies from a high predation population had lower aggression rates than their low predation counterpart, but male courtship and sneaking attempts did not differ between populations. Surprisingly, females were just as aggressive as males when competing for mates. These results highlight the trade-offs between antipredator and agonistic behaviour, which may affect sexual selection pressures in wild populations. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. The integration of gas and electricity: potential effects on competition in markets

    International Nuclear Information System (INIS)

    Lopez Milla, J.

    2007-01-01

    During the last years, an increasing number of gas and electricity companies have integrated their activities in both sectors. Following this trend, several Mergers and Acquisitions between gas and electricity companies have emerged, and some of them have been cross-borders operations that have given rise to multinational enterprises. This paper analyses the causes of the integration of gas and electricity activities, and examines its implications on regulation and competition policy, showing that these changes in the energy industry raise new challenges and compel to adopt new measures in that field of the economic policy. (Author) 25 refs

  18. Belowground induction by Delia radicum or phytohormones affect aboveground herbivore communities on field-grown broccoli

    Directory of Open Access Journals (Sweden)

    Sandra Prisca Pierre

    2013-08-01

    Full Text Available Induced plant defence in response to phytophagous insects is a well described phenomenon. However, so far little is known about the effect of induced plant responses on subsequently colonizing herbivores in the field. Broccoli plants were induced in the belowground compartment using (i infestation by the root-herbivore Delia radicum, (ii root application of jasmonic acid (JA or (iii root application of salicylic acid (SA. The abundance of D. radicum and six aboveground herbivores displaying contrasting levels of host specialisation were surveyed for five weeks. Our study showed that the response of herbivores was found to differ from one another, depending on the herbivore species, its degree of specialisation and the root treatment. The abundance of the root herbivore D. radicum and particularly the number of emerging adults was decreased by both phytohormone treatments, while the number of D. radicum eggs was increased on conspecific infested plants. The root infestation exhibited moderate effects on the aboveground community. The abundance of the aphid Brevicoryne brassicae was strongly increased on D. radicum infested plants, but the other species were not impacted. Root hormone applications exhibited a strong effect on the abundance of specialist foliar herbivores. A higher number of B. brassicae and Pieris brassicae and a lower number of Plutella xylostella were found on JA treated plants. On SA treated plants we observed a decrease of the abundance of B. brassicae, Pi. rapae and P. xylostella. Surprisingly, generalist species, Mamestra brassicae and Myzus persicae were not affected by root induction treatments. Finally, root treatments had no significant effect on either glucosinolate profiles of the heads or on plant quality parameters. These results are discussed from the perspective of below- aboveground interactions and adaptations of phytophagous insects to induced plant responses according to their trophic specialisation level.

  19. Case competitions

    DEFF Research Database (Denmark)

    Schjoldager, Anne Gram

    2009-01-01

    The paper presents and discusses a teaching project with case competitions for MA students of specialised translation at the Aarhus School of Business, Aarhus University. Drawing on a series of online questionnaires, the paper ascertains how the project was evaluated by the participating students...

  20. The Effect of Shoot/Root Competition of Black night shade (Solanum nigrum on Growth and Seed Yield of Mung Bean (Vigna radiate L.

    Directory of Open Access Journals (Sweden)

    M Goldani

    2015-04-01

    Full Text Available In order to study the competition effects of Solanum nigrum on Vigna radiate yield, an additive experiment was conducts at Ferdowsi University of Mashhad experimental Greenhouse. The type of design was completely randomized block. Treatments included three density of Solanum nigrum (2, 4, and 6 plants m-2 and three types of competition (root, shoot and both of them planted at constant density of Vigna radiate plus weed free check in each block. The results indicated that competitions had significant effects (P

  1. Winners, losers, and posers: The effect of power poses on testosterone and risk-taking following competition.

    Science.gov (United States)

    Smith, Kristopher M; Apicella, Coren L

    2017-06-01

    A contribution to a special issue on Hormones and Human Competition. The effect of postural power displays (i.e. power poses) on hormone levels and decision-making has recently been challenged. While Carney et al. (2010) found that holding brief postural displays of power leads to increased testosterone, decreased cortisol and greater economic risk taking, this failed to replicate in a recent high-powered study (Ranehill et al. 2015). It has been put forward that subtle differences in social context may account for the differences in results. Power displays naturally occur within the context of competitions, as do changes in hormones, and researchers have yet to examine the effects of poses within this ecologically relevant context. Using a large sample of 247 male participants, natural winners and losers of a physical competition were randomly assigned to hold a low, neutral or high-power postural display. We found no main effect of pose type on testosterone, cortisol, risk or feelings of power. Winners assigned to a high-power pose had a relative, albeit small, rise in testosterone compared to winners who held neutral or low-power poses. For losers, we found little evidence that high-power poses lead to increased testosterone relative to those holding neutral or low-powered poses. If anything, the reverse was observed - losers had a reduction in testosterone after holding high-power poses. To the extent that changes in testosterone modulate social behaviors adaptively, it is possible that the relative reduction in testosterone observed in losers taking high-powered poses is designed to inhibit further "winner-like" behavior that could result in continued defeat and harm. Still, effects were small, multiple comparisons were made, and the results ran counter to our predictions. We thus treat these conclusions as preliminary. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. When Agony Begets Zealotry: The Differential Role of Globalization Threats in Mediating the Effect of Competitive Victimhood on Muslims’ Religious Fundamentalism

    NARCIS (Netherlands)

    Mashuri, A.; Zaduqisti, Esti; Sakdiah, Halimatus; Sukmawati, Fitri

    2015-01-01

    The current investigations examine how globalization signifying either identity threat or realistic threat has a differential role in mediating the effect of competitive victimhood on Muslims’ religious fundamentalism. Study 1 ( N= 119) revealed that identity globalization threat and not realistic

  3. Effects of Intraguild Predation: Evaluating Resource Competition between Two Canid Species with Apparent Niche Separation

    Directory of Open Access Journals (Sweden)

    Adam J. Kozlowski

    2012-01-01

    Full Text Available Many studies determine which habitat components are important to animals and the extent their use may overlap with competitive species. However, such studies are often undertaken after populations are in decline or under interspecific stress. Since habitat selection is not independent of interspecific stress, quantifying an animal's current landscape use could be misleading if the species distribution is suboptimal. We present an alternative approach by modeling the predicted distributions of two sympatric species on the landscape using dietary preferences and prey distribution. We compared the observed habitat use of kit foxes (Vulpes macrotis and coyotes (Canis latrans against their predicted distribution. Data included locations of kit foxes and coyotes, carnivore scat transects, and seasonal prey surveys. Although habitats demonstrated heterogeneity with respect to prey resources, only coyotes showed habitat use designed to maximize access to prey. In contrast, kit foxes used habitats which did not align closely with prey resources. Instead, habitat use by kit foxes represented spatial and behavioral strategies designed to minimize spatial overlap with coyotes while maximizing access to resources. Data on the distribution of prey, their dietary importance, and the species-specific disparities between predicted and observed habitat distributions supports a mechanism by which kit fox distribution is derived from intense competitive interactions with coyotes.

  4. An Evaluation on Effects of Total Quality Applications in Customer Relations Management on Sustainable Global Competition

    Directory of Open Access Journals (Sweden)

    Pinar Altinok

    2016-01-01

    Full Text Available The concept of globalization inherently necessitated knowing management technics that could adapt to fast changes. Assuming all other financial aspects are almost equal for companies, the only factor “that can create difference” within the global competition environment is “the human factor”. It draws attention in the way that among companies who set out with the same technical equipment, the companies who are successful in customer relations are able to render the global competition sustainable through approaches that are based on the human factor. In this area, the constructive influences of total quality management on the human, which is the main source that can manage information and turn it into speed and strength, positively reflect on companies and translate into advantages. Placing human at the center of the business, these approaches add new dimensions to changes and developments that will create differences in the global market in line with the versatile structure of business management and contribute to earnings that support economic growth.

  5. Mechanisms and ecological implications of plant-mediated interactions between belowground and aboveground insect herbivores

    NARCIS (Netherlands)

    Papadopoulou, G.V.; Dam, N.M. van

    2017-01-01

    Plant-mediated interactions between belowground (BG) and aboveground (AG) herbivores have received increasing interest recently. However, the molecular mechanisms underlying ecological consequences of BG–AG interactions are not fully clear yet. Herbivore-induced plant defenses are complex and

  6. Above-belowground interactions govern the course and impact of biological invasions

    DEFF Research Database (Denmark)

    Vestergård, Mette; Rønn, Regin; Ekelund, Flemming

    2015-01-01

    in an evolutionary and ecological context; in the case of invasive plants, we must have a major focus on above-belowground interactions. Thus, we discuss different theories that have been proposed to explain the course of invasions through interactions between plants and soil organisms. Further, a thorough analysis...

  7. Plant-Mediated Systemic Interactions Between Pathogens, Parasitic Nematodes, and Herbivores Above- and Belowground

    NARCIS (Netherlands)

    Biere, A.; Goverse, A.

    2016-01-01

    Plants are important mediators of interactions between aboveground (AG) and belowground (BG) pathogens, arthropod herbivores, and nematodes (phytophages). We highlight recent progress in our understanding of within- and cross-compartment plant responses to these groups of phytophages in terms of

  8. Plant-mediated systemic interactions between pathogens, parasitic nematodes, and herbivores above- and belowground

    NARCIS (Netherlands)

    Biere, A.; Goverse, Aska

    2016-01-01

    Plants are important mediators of interactions between aboveground (AG) and belowground (BG) pathogens, arthropod herbivores, and nematodes (phytophages). We highlight recent progress in our understanding of within and cross-compartment plant responses to these groups of phytophages in terms of

  9. Identification of Biologically Relevant Compounds in Aboveground and Belowground Induced Volatile Blends

    NARCIS (Netherlands)

    Dam, van N.M.; Qiu, B.L.; Hordijk, C.A.; Vet, L.E.M.; Jansen, J.J.

    2010-01-01

    Plants under attack by aboveground herbivores emit complex blends of volatile organic compounds (VOCs). Specific compounds in these blends are used by parasitic wasps to find their hosts. Belowground induction causes shifts in the composition of aboveground induced VOC blends, which affect the

  10. Belowground carbon distribution in a pinon-juniper / short grass prairie site

    Science.gov (United States)

    John Harrington

    2008-01-01

    Pinon-juniper woodlands encompass over 22.5 million hectares in the Western United States. However, little is known about the ability of these ecosystems to sequester carbon. This paper presents the preliminary results of an investigation on the belowground carbon distribution in a pinon-juniper/short grass prarie site in north-central New Mexico. Using a systematic...

  11. Belowground plant biomass of mountain grassland affected by regular and manipulated rainfall in 2006 and 2007

    Czech Academy of Sciences Publication Activity Database

    Fiala, Karel; Tůma, Ivan

    2008-01-01

    Roč. 1, č. 1 (2008), s. 19-22 ISSN 1803-2451 R&D Projects: GA ČR(CZ) GA526/06/0556 Institutional research plan: CEZ:AV0Z60050516 Keywords : root increments * total belowground biomass * manipulated rainfall Subject RIV: EF - Botanics

  12. Above-ground and below-ground plant responses to fertilization in two subarctic ecosystems

    NARCIS (Netherlands)

    Veen, G.F.; Sundqvist, Maja K.; Metcalfe, D.; Wilson, S.D.

    2015-01-01

    Soil nutrient supply is likely to change in the Arctic due to altered process rates associated with climate change. Here, we compare the responses of herbaceous tundra and birch forest understory to fertilization, considering both above- and below-ground responses. We added nitrogen and phosphorus

  13. Fertilization Increases Below-Ground Carbon Sequestration of Loblolly Pine Plantations

    Science.gov (United States)

    K.H. Johnsen; J.R. Butnor; C. Maier; R. Oren; R. Pangle; L. Samuelson; J. Seiler; S.E. McKeand; H.L. Allen

    2001-01-01

    The extent of fertilization of southern pine forests is increasing rapidly; industrial fertilization increased from 16,200 ha per year in 1988, to 344,250 ha in 1998. Fertilization increases stand productivity and can increase carbon (C) sequestration by: 1) increasing above-ground standing C; 2) increasing C stored in forest products; and 3) increasing below-ground...

  14. Belowground carbon cycling in a humid tropical forest decreases with fertilization

    Science.gov (United States)

    C. Giardina; D. Binkley; M. Ryan; J. Fownes

    2004-01-01

    Only a small fraction of the carbon (C) allocated belowground by trees is retained by soils in long-lived, decay-resistant forms, yet because of the large magnitude of terrestrial primary productivity, even small changes in C allocation or retention can alter terrestrial C storage. The humid tropics exert a disproportionately large influence over terrestrial C storage...

  15. Interactions Between a Belowground Herbivore and Primary and Secondary Root Metabolites in Wild Cabbage

    NARCIS (Netherlands)

    Van Geem, Moniek; Harvey, J.A.; Cortesero, A.M.; Raaijmakers, C.E.; Gols, R.

    2015-01-01

    Plants are attacked by both above- and belowground herbivores. Toxic secondary compounds are part of the chemical defense arsenal of plants against a range of antagonists, and are subject to genetic variation. Plants also produce primary metabolites (amino acids, nutrients, sugars) that function as

  16. Interactions between a belowground herbivore and primary and secondary root metabolites in wild cabbage

    NARCIS (Netherlands)

    Van Geem, Moniek; Harvey, Jeff; Cortesero, A.M.; Raaijmakers, Ciska; Gols, R.

    2015-01-01

    Plants are attacked by both above- and belowground herbivores. Toxic secondary compounds are part of the chemical defense arsenal of plants against a range of antagonists, and are subject to genetic variation. Plants also produce primary metabolites (amino acids, nutrients, sugars) that function as

  17. Arbuscular mycorrhizal fungi alter above- and below-ground chemical defense expression differentially among Asclepias species

    Science.gov (United States)

    Vannette, Rachel L.; Hunter, Mark D.; Rasmann, Sergio

    2013-01-01

    Below-ground (BG) symbionts of plants can have substantial influence on plant growth and nutrition. Recent work demonstrates that mycorrhizal fungi can affect plant resistance to herbivory and the performance of above- (AG) and BG herbivores. Although these examples emerge from diverse systems, it is unclear if plant species that express similar defensive traits respond similarly to fungal colonization, but comparative work may inform this question. To examine the effects of arbuscular mycorrhizal fungi (AMF) on the expression of chemical resistance, we inoculated 8 species of Asclepias (milkweed)—which all produce toxic cardenolides—with a community of AMF. We quantified plant biomass, foliar and root cardenolide concentration and composition, and assessed evidence for a growth-defense tradeoff in the presence and absence of AMF. As expected, total foliar and root cardenolide concentration varied among milkweed species. Importantly, the effect of mycorrhizal fungi on total foliar cardenolide concentration also varied among milkweed species, with foliar cardenolides increasing or decreasing, depending on the plant species. We detected a phylogenetic signal to this variation; AMF fungi reduced foliar cardenolide concentrations to a greater extent in the clade including A. curassavica than in the clade including A. syriaca. Moreover, AMF inoculation shifted the composition of cardenolides in AG and BG plant tissues in a species-specific fashion. Mycorrhizal inoculation changed the relative distribution of cardenolides between root and shoot tissue in a species-specific fashion, but did not affect cardenolide diversity or polarity. Finally, a tradeoff between plant growth and defense in non-mycorrhizal plants was mitigated completely by AMF inoculation. Overall, we conclude that the effects of AMF inoculation on the expression of chemical resistance can vary among congeneric plant species, and ameliorate tradeoffs between growth and defense. PMID:24065971

  18. Competitive effects of introduced annual weeds on some native and reclamation species in the Powder River Basin, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Allen, E.B.; Knight, D.H.

    1980-01-01

    Four experiments were conducted to examine the competitive effects of introduced annual weeds on certain native and reclamation species. The first experiment was initiated by discing three sites in the Powder River Basin, Wyoming, at three distances from introduced weed seed sources. Introduced weed colonization was greatest when a seed source was located nearby. Higher weed cover resulted in reductions of percent cover, density, and richness of the native species. The second experiment was conducted in the greenhouse and was designed to determine if there are changes in response of S. kali and the native grasses Agropyron smithii and Bouteloua gracilis to competition and water regime. Both grass species had lower biomass and higher stomatal resistance when growing in mixed culture with S. kali than in pure culture in the dry regime, but there were no significant differences in the wet regime. In general, the difference in plant response between mixed and pure cultures was more pronounced in the dry than in the wet regime. The third study was a greenhouse experiment on germination and competition of S. kali (a C/sub 4/ species) with native species Lepidium densiflorum (C/sub 3/), Chenopodium pratericola (C/sub 3/), A. smithii (C/sub 3/), and B. gracilis (C/sub 4/) under May, June, and July temperature regimes. Salsola kali germinated equally well in all three regimes, but the other C/sub 4/ species had highest germination in the July regime and the C/sub 3/ species in the May and June regimes. The fourth study was designed to examine the effect of weed colonization on the success of mine reclamation. Little effect was observed, but colonization by introduced annuals was very low. (ERB)

  19. The Effect Of Customer Demand And Supplier Performance In Competitive Strategy And Business Performance Case Of Fixed Broadband In Indonesia

    Directory of Open Access Journals (Sweden)

    Rina D. Pasaribu

    2015-08-01

    Full Text Available Broadband telecommunication is significantly important to support and improve countrys competitiveness level. However Indonesia performance especially in Fixed Broadband is poor as the penetration rate is very low and far behind from other ASEAN countries. The industry is served by multi operators with one dominant operator. This dominant operator will be studied representing the industry in this study. A qualitative study Pasaribu et al. 2015 related to this paper has found that poor fulfillment of Customer Demand and poor Supplier Performance are two dominant external factors that cause the low performance. A model is proposed to frame the work it consists of four variables Customer Demand Supplier Performance Competitive Strategy and Business Performance. This study aims is use that Pasaribu et al. model directly to business units level to identify and analyze the relationships within the model and significance level of each relationship accordingly. By understanding the priority levels the improvement program could be more effectively planned and implemented. This study is expected to contribute on Fixed Broadband research wich is still very rare especially in Indonesia The research methodology is quantitative methods using survey technique. The respondents are management and customers of the dominant operator business units. Clustering by province regions gave 32 samples from the population of 58 business units. Partial Least Square modelling was used to analise the datas. The main result of this study is that the most significant relationship in the model is Supplier Performance to Competitive Strategy. Furthermore from indicators of Supplier Performance it was found that Quality Relationship has a very high effect among other indicators. By prioritizing these significant constructs it could be expected the related improvement program could be more effective.

  20. The Interaction between Root Herbivory and Competitive Ability of Native and Invasive-Range Populations of Brassica nigra.

    Directory of Open Access Journals (Sweden)

    Ayub M O Oduor

    Full Text Available The evolution of increased competitive ability (EICA hypothesis predicts that escape from intense herbivore damage may enable invasive plants to evolve higher competitive ability in the invasive range. Below-ground root herbivory can have a strong impact on plant performance, and invasive plants often compete with multiple species simultaneously, but experimental approaches in which EICA predictions are tested with root herbivores and in a community setting are rare. Here, we used Brassica nigra plants from eight invasive- and seven native-range populations to test whether the invasive-range plants have evolved increased competitive ability when competing with Achillea millefolium and with a community (both with and without A. millefolium. Further, we tested whether competitive interactions depend on root herbivory on B. nigra by the specialist Delia radicum. Without the community, competition with A. millefolium reduced biomass of invasive- but not of native-range B. nigra. With the community, invasive-range B. nigra suffered less than native-range B. nigra. Although the overall effect of root herbivory was not significant, it reduced the negative effect of the presence of the community. The community produced significantly less biomass when competing with B. nigra, irrespective of the range of origin, and independent of the presence of A. millefolium. Taken together, these results offer no clear support for the EICA hypothesis. While native-range B. nigra plants appear to be better in dealing with a single competitor, the invasive-range plants appear to be better in dealing with a more realistic multi-species community. Possibly, this ability of tolerating multiple competitors simultaneously has contributed to the invasion success of B. nigra in North America.

  1. The Interaction between Root Herbivory and Competitive Ability of Native and Invasive-Range Populations of Brassica nigra

    Science.gov (United States)

    Oduor, Ayub M. O.; Stift, Marc; van Kleunen, Mark

    2015-01-01

    The evolution of increased competitive ability (EICA) hypothesis predicts that escape from intense herbivore damage may enable invasive plants to evolve higher competitive ability in the invasive range. Below-ground root herbivory can have a strong impact on plant performance, and invasive plants often compete with multiple species simultaneously, but experimental approaches in which EICA predictions are tested with root herbivores and in a community setting are rare. Here, we used Brassica nigra plants from eight invasive- and seven native-range populations to test whether the invasive-range plants have evolved increased competitive ability when competing with Achillea millefolium and with a community (both with and without A. millefolium). Further, we tested whether competitive interactions depend on root herbivory on B. nigra by the specialist Delia radicum. Without the community, competition with A. millefolium reduced biomass of invasive- but not of native-range B. nigra. With the community, invasive-range B. nigra suffered less than native-range B. nigra. Although the overall effect of root herbivory was not significant, it reduced the negative effect of the presence of the community. The community produced significantly less biomass when competing with B. nigra, irrespective of the range of origin, and independent of the presence of A. millefolium. Taken together, these results offer no clear support for the EICA hypothesis. While native-range B. nigra plants appear to be better in dealing with a single competitor, the invasive-range plants appear to be better in dealing with a more realistic multi-species community. Possibly, this ability of tolerating multiple competitors simultaneously has contributed to the invasion success of B. nigra in North America. PMID:26517125

  2. Party-state relationship, an effect of the political competition. The party system and patronage in Romanian politics

    Directory of Open Access Journals (Sweden)

    Irina Lonean

    2012-06-01

    Full Text Available The article examines the party-state relationship in post-communist Romania. It shows the connections between the existence of patronage, corruption and the states’ weak administrative capacity, on one hand, and the dynamics of the political party system, as an explanatory variable, on the other hand. The instability of the political parties in Romania and their changing relations within the system make the electorates’ task of anticipating and sanctioning their politics impossible. Consequently, the political parties have the possibility of extracting resources from the state without being held accountable in elections, as an effect of their dynamic, but non-robust competition.

  3. Magnetic field effect on the pairing competition in quasi-one-dimensional organic superconductors (TMTSF){sub 2}X

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Hirohito, E-mail: aizawa@vivace.e-one.uec.ac.j [Department of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Kuroki, Kazuhiko [Department of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Tanaka, Yukio [Department of Applied Physics, Nagoya University, Nagoya 464-8603 (Japan)

    2010-06-01

    We microscopically study the effect of the magnetic field (Zeeman splitting) on the superconducting state in a model for quasi-one-dimensional organic conductors (TMTSF){sub 2}X. Using random phase approximation, we investigate the competition between spin singlet, spin triplet pairings and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We obtain a phase diagram in the T (temperature)-h{sub z} (field) space. We show that consecutive transitions from singlet pairing to FFLO and further to S{sub z}=1 triplet pairing can take place upon increasing the magnetic field when 2k{sub F} charge fluctuations coexist with 2k{sub F} spin fluctuations.

  4. Magnetic field effect on the pairing competition in quasi-one-dimensional organic superconductors (TMTSF)2X

    International Nuclear Information System (INIS)

    Aizawa, Hirohito; Kuroki, Kazuhiko; Tanaka, Yukio

    2010-01-01

    We microscopically study the effect of the magnetic field (Zeeman splitting) on the superconducting state in a model for quasi-one-dimensional organic conductors (TMTSF) 2 X. Using random phase approximation, we investigate the competition between spin singlet, spin triplet pairings and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We obtain a phase diagram in the T (temperature)-h z (field) space. We show that consecutive transitions from singlet pairing to FFLO and further to S z =1 triplet pairing can take place upon increasing the magnetic field when 2k F charge fluctuations coexist with 2k F spin fluctuations.

  5. Aboveground vs. Belowground Carbon Stocks in African Tropical Lowland Rainforest: Drivers and Implications.

    Directory of Open Access Journals (Sweden)

    Sebastian Doetterl

    Full Text Available African tropical rainforests are one of the most important hotspots to look for changes in the upcoming decades when it comes to C storage and release. The focus of studying C dynamics in these systems lies traditionally on living aboveground biomass. Belowground soil organic carbon stocks have received little attention and estimates of the size, controls and distribution of soil organic carbon stocks are highly uncertain. In our study on lowland rainforest in the central Congo basin, we combine both an assessment of the aboveground C stock with an assessment of the belowground C stock and analyze the latter in terms of functional pools and controlling factors.Our study shows that despite similar vegetation, soil and climatic conditions, soil organic carbon stocks in an area with greater tree height (= larger aboveground carbon stock were only half compared to an area with lower tree height (= smaller aboveground carbon stock. This suggests that substantial variability in the aboveground vs. belowground C allocation strategy and/or C turnover in two similar tropical forest systems can lead to significant differences in total soil organic C content and C fractions with important consequences for the assessment of the total C stock of the system.We suggest nutrient limitation, especially potassium, as the driver for aboveground versus belowground C allocation. However, other drivers such as C turnover, tree functional traits or demographic considerations cannot be excluded. We argue that large and unaccounted variability in C stocks is to be expected in African tropical rain-forests. Currently, these differences in aboveground and belowground C stocks are not adequately verified and implemented mechanistically into Earth System Models. This will, hence, introduce additional uncertainty to models and predictions of the response of C storage of the Congo basin forest to climate change and its contribution to the terrestrial C budget.

  6. Aboveground vs. Belowground Carbon Stocks in African Tropical Lowland Rainforest: Drivers and Implications.

    Science.gov (United States)

    Doetterl, Sebastian; Kearsley, Elizabeth; Bauters, Marijn; Hufkens, Koen; Lisingo, Janvier; Baert, Geert; Verbeeck, Hans; Boeckx, Pascal

    2015-01-01

    African tropical rainforests are one of the most important hotspots to look for changes in the upcoming decades when it comes to C storage and release. The focus of studying C dynamics in these systems lies traditionally on living aboveground biomass. Belowground soil organic carbon stocks have received little attention and estimates of the size, controls and distribution of soil organic carbon stocks are highly uncertain. In our study on lowland rainforest in the central Congo basin, we combine both an assessment of the aboveground C stock with an assessment of the belowground C stock and analyze the latter in terms of functional pools and controlling factors. Our study shows that despite similar vegetation, soil and climatic conditions, soil organic carbon stocks in an area with greater tree height (= larger aboveground carbon stock) were only half compared to an area with lower tree height (= smaller aboveground carbon stock). This suggests that substantial variability in the aboveground vs. belowground C allocation strategy and/or C turnover in two similar tropical forest systems can lead to significant differences in total soil organic C content and C fractions with important consequences for the assessment of the total C stock of the system. We suggest nutrient limitation, especially potassium, as the driver for aboveground versus belowground C allocation. However, other drivers such as C turnover, tree functional traits or demographic considerations cannot be excluded. We argue that large and unaccounted variability in C stocks is to be expected in African tropical rain-forests. Currently, these differences in aboveground and belowground C stocks are not adequately verified and implemented mechanistically into Earth System Models. This will, hence, introduce additional uncertainty to models and predictions of the response of C storage of the Congo basin forest to climate change and its contribution to the terrestrial C budget.

  7. EDITORIAL: Physics competitions Physics competitions

    Science.gov (United States)

    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

  8. Planning the International Competition Schedules for the Health of Elite Athletes: A 21-Year Retrospective Study Evaluating the Effectiveness and Economic Impact in an Olympic Sport.

    Science.gov (United States)

    Malagoni, Anna Maria; Lamberti, Nicola; Carrabre, James E; Litmanen, Hannu; Jeannier, Pierre; Zhukovskaja, Larisa; Dal Follo, Donatella; Zambon, Christel; Resch, Nicole; Manfredini, Fabio

    2015-01-01

    The increased number of trips and competitions scheduled in the international agonistic calendars meets commercial demands while acting as a source of stress for the athletes. A model, developed in biathlons to monitor the so-called competition load, revealed an upward trend over time. The aim of this study was to evaluate, in a 21-year period, the effects of the International Biathlon Union's rescheduling of the competitive calendars to control the competition load, as well as its stability over time and the economic impact of this intervention. For each season competition, the load factors from the international agonistic calendar (number of venues/events, competition days/distance) were considered, and the athletes' daily and maximal stress scores were calculated. The calendar rescheduling, which started in 2001, involved the length of competitions, number of resting days and frequency of travels. Data from the period pre (1994-2000) and post (2001-2007) the intervention, as well as follow-up (2008-2015), were compared and analyzed in relation to the federation's budget. The competition load and athletes' daily stress score progressively increased pre, plateaued post and remained stable in follow-up. Their annual variations within the final two periods were significantly lower than in the pre period, in spite of the higher average values. The maximal stress score decreased over time. The direct correlation between most of the competition load factors with the economic budget present in pre was lost in post and follow-up. Similarly, the athletes' daily stress score had a stable trend in post and follow-up, while budget continued to increase. The management of an athlete's potential source of stress by an international federation stabilized the competition load over time, but it did not affect the budget. Furthermore, it uncoupled the relationship between the athlete's effort and federation income.

  9. Planning the International Competition Schedules for the Health of Elite Athletes: A 21-Year Retrospective Study Evaluating the Effectiveness and Economic Impact in an Olympic Sport.

    Directory of Open Access Journals (Sweden)

    Anna Maria Malagoni

    Full Text Available The increased number of trips and competitions scheduled in the international agonistic calendars meets commercial demands while acting as a source of stress for the athletes. A model, developed in biathlons to monitor the so-called competition load, revealed an upward trend over time. The aim of this study was to evaluate, in a 21-year period, the effects of the International Biathlon Union's rescheduling of the competitive calendars to control the competition load, as well as its stability over time and the economic impact of this intervention.For each season competition, the load factors from the international agonistic calendar (number of venues/events, competition days/distance were considered, and the athletes' daily and maximal stress scores were calculated. The calendar rescheduling, which started in 2001, involved the length of competitions, number of resting days and frequency of travels. Data from the period pre (1994-2000 and post (2001-2007 the intervention, as well as follow-up (2008-2015, were compared and analyzed in relation to the federation's budget.The competition load and athletes' daily stress score progressively increased pre, plateaued post and remained stable in follow-up. Their annual variations within the final two periods were significantly lower than in the pre period, in spite of the higher average values. The maximal stress score decreased over time. The direct correlation between most of the competition load factors with the economic budget present in pre was lost in post and follow-up. Similarly, the athletes' daily stress score had a stable trend in post and follow-up, while budget continued to increase.The management of an athlete's potential source of stress by an international federation stabilized the competition load over time, but it did not affect the budget. Furthermore, it uncoupled the relationship between the athlete's effort and federation income.

  10. The Effect of Artificial Mowing on the Competition of Phragmites australis and Spartina alterniflora in the Yangtze Estuary

    Directory of Open Access Journals (Sweden)

    Yue Yuan

    2017-01-01

    Full Text Available Spartina alterniflora Loisel. is one of the most invasive species in the world. However, little is known about the role of artificial mowing in its invasiveness and competiveness. In this work, we studied the effect of mowing on its interspecific interactions with native species Phragmites australis (Cav. Trin ex Steud of the Yangtze Estuary, China. We calculated their relative neighbor effect (RNE index, effect of relative crowding (Dr index, and interaction strength (I index. The results showed that the RNE of Phragmites australis and Spartina alterniflora was 0.354 and 0.619, respectively, and they have competitive interactions. The mowing treatments can significantly influence the RNE of Phragmites australis and Spartina alterniflora on each other. Concretely, the RNE of Spartina alterniflora in the removal treatments was significantly higher than the value in the controls. But the RNE of Phragmites australis in the removal treatments was significantly lower than the value in the controls. Meanwhile, Dr of the two species on the targets was higher in the removal treatments than that in the controls, and the opposite was for I. We concluded that artificial mowing could promote the invasion of Spartina alterniflora by increasing its competitive performance compared with native species.

  11. Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study.

    Science.gov (United States)

    Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh D; Liu, Zhengwen

    2015-03-01

    Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems.

  12. The energy administration, an effective alternative to improve the managerial competitiveness

    International Nuclear Information System (INIS)

    Borroto Nordelo, Anibal; Lapido Rodriguez, Margarita; Monteagudo Yanes, Jose and others

    2005-01-01

    This region's actual development is in need of immediate actions to reduce costs, protect the environment and increase company competitiveness versus a growing global economy. Energetic efficiency represents on of the principal opportunities to meets these goals. Numerous studies in companies in Cuba, Mexico, Colombia and Ecuador have shown poor energetic management and cleared that there are many costs reduction possibilities if they create technical capacities within the industry. The center of energy and environmental studies in the university of Cien Fuegos, created the total management of efficient energy, its main objective is to create in technical and organizational capacities in the corporations. Known as TGTEE, Total Management of Efficient Energy, has widened its popularity among the region and has achieved significant economic and social results, and leads to the construction of an energetic and environmental culture

  13. Effect of competitive ions on the arsenic removal by mesoporous hydrous zirconium oxide from drinking water

    Energy Technology Data Exchange (ETDEWEB)

    Bortun, Anatoly; Bortun, Mila; Pardini, James [MEL Chemicals Inc., 500 Barbertown Point Breeze Road, Flemington, NJ 08822 (United States); Khainakov, Sergei A. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo, C/ Julian Claveria, 8, 33006 Oviedo (Spain); Garcia, Jose R., E-mail: jrgm@uniovi.es [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo, C/ Julian Claveria, 8, 33006 Oviedo (Spain)

    2010-11-15

    Adsorption properties of 302-type commercially available hydrous zirconium oxide (302-HZO) towards arsenic and some competitive anions and cations have been studied under batch and column conditions. Due to amphoteric properties, anion exchange performance of hydrous zirconium oxide is pH dependent. Media exhibits high affinity towards arsenic in a broad pH range, with high adsorption capacity at pH < 8. It was shown that silicate and phosphate ions are arsenic's main competitors affecting media adsorption capacity. Presence of transition metal cations in <1 ppm does not affect 302-HZO capacity on arsenic, whereas alkaline-earth cations improve arsenic removal. The possibility for significant increase of 302-HZO adsorption capacity on arsenic at pH > 8 by using 'solid acidifier' technique is discussed. Results of 302-HZO field trials are presented.

  14. Density and relative frequency effects on competitive interactions and resource use in pea–barley intercrops

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, H.; Andersen, H.K.; Jørnsgaard, B.

    2006-01-01

    . Earlier seedling emergence gave barley an initial growth advantage, assessed using the relative efficiency index (REIc), whereas pea was in general more growth efficient once the initial growth phase had been passed. This reversal in relative growth efficiency along with the observation that early barley...... of the growing period and more so in the pea dominated intercrop. At the final harvest land equivalent ratios (LER) of 0.9-1.2 express resource complementarity in almost all studied intercrops, complementarity that was not directly affected by changes in plant density or relative frequency. Intercropped pea did...... or specific grain yield composition are wanted. Keywords: Competition dynamics; Grain quality; Hordeum vulgare; Intercropping; Nitrogen use; Organic farming; Pisum sativum; Weeds; Yield Abbreviations: IC, mixed intercropping; LER, land equivalent ratio; N, nitrogen; REIc, relative efficiency index; SC, sole...

  15. Lethal effects of habitat degradation on fishes through changing competitive advantage.

    Science.gov (United States)

    McCormick, Mark I

    2012-10-07

    Coral bleaching has caused catastrophic changes to coral reef ecosystems around the world with profound ecological, social and economic repercussions. While its occurrence is predicted to increase in the future, we have little understanding of mechanisms that underlie changes in the fish community associated with coral degradation. The present study uses a field-based experiment to examine how the intensity of interference competition between juveniles of two species of damselfish changes as healthy corals degrade through thermal bleaching. The mortality of a damselfish that is a live coral specialist (Pomacentrus moluccensis) increased on bleached and dead coral in the presence of the habitat generalist (Pomacentrus amboinensis). Increased mortality of the specialist was indirectly owing to enhanced aggression by the generalist forcing the specialist higher up and further away from shelter on bleached and dead coral. Evidence from this study stresses the importance of changing interspecific interactions to community dynamics as habitats change.

  16. Logo competition

    CERN Multimedia

    Staff Association

    2013-01-01

    Award of the prizes The price ceremony for the Staff Association’s new logo competition which took place on Friday 1st March at 5 p.m. was a big success. The first prize, an Ezee Suisse electric bike, was won by Paulo Rios, from Portugal. In his absence, the bike was handed to his brother Vitor. The other five winners of the competition also received their prize: Go Sport vouchers. A peize draw was then organized to award 22 other participants with prizes offered by our commercial partners (Aquaparc, BCGE, L’Occitane, Passeport Gourmand, Sephora, Theater La Comédie de Genève), whom we would like to warmly thank. After all prices were distributed the evening continued with discussions around a friendly drink.

  17. Effects of Generational Competition and Substitution on Late Labour Participation and Labour Market Exit from a Multilevel Perspective

    Directory of Open Access Journals (Sweden)

    Henriette Engelhardt

    2013-12-01

    Full Text Available In this paper, we investigate the effects of demographic, economic and labour market structures on labour market participation and on the transition to inactivity (exit for older males in eleven European countries. Theoretically, our analysis is guided by considerations of intragenerational competition and intergenerational substitution. Following Easterlin’s hypothesis that intragenerational competition rises with cohort size, we assume a negative effect of cohort size on labour market participation and a positive effect on early exit from the labour market. Taking into account that different cohorts are substitutes at least to a certain extent, we assume that the probability of an early exit will be reduced by a high intergenerational exchange ratio in favour of older workers. Thus, labour market participation is influenced by the populations’ age structure both when entering the labour force and during the career. Moreover, low shares of graduates in older cohorts are expected to reduce older workers’ chances of labour market participation. In addition to demographic structures, general economic conditions, such as per capita GDP and its development over time, act both to further and to hamper the employment of older workers. Additionally, labour market structures, such as unemployment rates, the extent of part-time work or the amount of service jobs influence individual participation and the transition to inactivity. To test these hypotheses, we use merged data from the first two waves of SHARE and macro-level indicators from Eurostat. We estimate a two-level random-intercept logit model which allows us to determine the share of variance in international late careers that can be attributed to country-specific factors and can quantify the relative impact of specific socio-demographic and socio-economic backgrounds. Our results imply that cross-national variance in labour market participation is mainly driven by the instance of long

  18. Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets.

    Science.gov (United States)

    Araújo, Márcio S; Guimarães, Paulo R; Svanbäck, Richard; Pinheiro, Aluisio; Guimarães, Paulo; Dos Reis, Sérgio F; Bolnick, Daniel I

    2008-07-01

    Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanbäck and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.

  19. The Effects of Bench Press Variations in Competitive Athletes on Muscle Activity and Performance

    Directory of Open Access Journals (Sweden)

    Saeterbakken Atle Hole

    2017-06-01

    Full Text Available The aim of the study was to compare the EMG activity performing 6RM competition style bench press (flat bench-wide grip with 1 medium and narrow grip widths on a flat bench and 1 inclined and declined bench positions with a wide grip. Twelve bench press athletes competing at national and international level participated in the study. EMG activity was measured in the pectoralis major, anterior and posterior deltoid, biceps brachii, triceps brachii and latissimus dorsi. Non-significant differences in activation were observed between the three bench positions with the exception of 58.5-62.6% lower triceps brachii activation, but 48.3-68.7% greater biceps brachii activation in the inclined bench compared with the flat and declined bench position. Comparing the three grip widths, non-significant differences in activations were observed, with the exception of 25.9-30.5% lower EMG activity in the biceps brachii using a narrow grip, compared to the medium and wide grip conditions. The 6-RM loads were 5.8-11.1% greater using a medium and wide grip compared to narrow grip width and 18.5-21.5% lower in the inclined bench position compared with flat and declined. Comparing the EMG activity during the competition bench press style with either the inclined and declined bench position (wide grip or using a narrow and medium grip (flat bench, only resulted in different EMG activity in the biceps- and triceps brachii. The 6RM loads varied with each bench press variation and we recommend the use of a wide grip on a flat bench during high load hypertrophy training to bench press athletes.

  20. Optimal Competition : A Benchmark for Competition Policy

    NARCIS (Netherlands)

    Boone, J.

    2003-01-01

    This paper introduces optimal competition: the best form of competition in an industry that a competition authority can achieve under the information constraint that it cannot observe firms' effciency levels.We show that the optimal competition outcome in an industry becomes more competitive as more