WorldWideScience

Sample records for belowground competition effects

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

    Science.gov (United States)

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

    2016-01-01

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

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

    OpenAIRE

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

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenho...

  3. Interactive effects of above- and belowground herbivory and plant competition on plant growth and defence

    NARCIS (Netherlands)

    Jing, Jingying; Raaijmakers, Ciska; Kostenko, Olga; Kos, Martine; Mulder, P.P.J.; Bezemer, T. Martijn

    2015-01-01

    Competition and herbivory are two major factors that can influence plant growth and plant defence. Although these two factors are often studied separately, they do not operate independently. We examined how aboveground herbivory by beet armyworm larvae (Spodoptera exigua) and belowground herbivory b

  4. Aboveground and belowground competition between willow Salix caprea its understory

    Science.gov (United States)

    Mudrák, Ondřej; Hermová, Markéta; Frouz, Jan

    2016-04-01

    The effects of aboveground and belowground competition with the willow S. caprea on its understory plant community were studied in unreclaimed post-mining sites. Belowground competition was evaluated by comparing (i) frames inserted into the soil that excluded woody roots (frame treatment), (ii) frames that initially excluded woody root growth but then allowed regrowth of the roots (open-frame treatment), and (iii) undisturbed soil (no-frame treatment). These treatments were combined with S. caprea thinning to assess the effect of aboveground competition. Three years after the start of the experiment, aboveground competition from S. caprea (as modified by thinning of the S. caprea canopy) had not affected understory biomass or species number but had affected species composition. In contrast, belowground competition significantly affected both the aboveground and belowground biomass of the understory. The aboveground biomass of the understory was greater in the frame treatment (which excluded woody roots) than in the other two treatments. The belowground biomass of the understory was greater in the frame than in the open-frame treatment. Unlike aboveground competition (light availability), belowground competition did not affect understory species composition. Our results suggest that S. caprea is an important component during plant succession on post-mining sites because it considerably modifies its understory plant community. Belowground competition is a major reason for the low cover and biomass of the herbaceous understory in S. caprea stands on post-mining sites.

  5. 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.

  6. 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.

  7. Effects of aboveground and belowground competition between grass and tree on elm seedlings growth in Horqin Sandy Land%地上竞争与地下竞争对科尔沁沙地榆树幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    唐毅; 蒋德明; 陈卓; 押田敏雄

    2011-01-01

    榆树疏林草原对科尔沁沙地植被恢复和景观保护有着重要意义.本文采用双因素两水平控制试验,从幼苗生物量、地下/地上生物量、茎高、根茎比、叶片数等方面,研究了草-树地上、地下竞争对科尔沁沙地榆树幼苗生长的影响.结果表明:对于1年生榆树幼苗,单株平均生物量表现为无竞争>地上竞争>全竞争>地下竞争;地下/地上生物量表现为地下竞争>全竞争>无竞争>地上竞争;幼苗高度表现为地上竞争>无竞争>全竞争>地下竞争;根茎比表现为地下竞争>全竞争>无竞争>地上竞争;叶片数表现为地上竞争>无竞争>地下竞争>全竞争.地下竞争对1年生榆树幼苗生长影响显著,而地上竞争对榆树幼苗生长无显著影响.地上竞争与地下竞争对2年生榆树幼苗生长的影响均不显著.科尔沁沙地草本植物对榆树幼苗生长的影响主要通过地下竞争的方式实现,但地下竞争并没有改变榆树幼苗的资源分配方式.随榆树幼苗龄级的增长,草本植物竞争作用的影响逐渐减弱.%Elm sparse woodland steppe plays an important role in vegetation restoration and landscape protection in Horqin Sandy Land. In this paper, a two-factor and two-level field experiment was conducted to explore the effects of aboveground and belowground competition between grass and tree on the growth of elm seedlings in the Sandy Land. Five aspects were considered, I. E. , seedling biomass, belowground biomass/aboveground biomass, stem height, ratio of root to stem, and leaf number. For the one-year-old elm seedlings, their biomass showed a trend of no competition > aboveground competition > full competition > belowground competition, belowground biomass / aboveground biomass showed a trend of belowground competition > full competition > no competition > aboveground competition, stem height showed a trend of aboveground competition > no competition

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

    Directory of Open Access Journals (Sweden)

    Francisco M Padilla

    Full Text Available 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 regarding root interactions is limited, as molecular methods quantifying species abundance belowground have only recently become available. PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: 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. Roots in space: a spatially explicit model for below-ground competition in plants.

    Science.gov (United States)

    O'Brien, Erin E; Brown, Joel S; Moll, Jason D

    2007-04-01

    Game theory provides an untapped framework for predicting how below-ground competition will influence root proliferation in a spatially explicit environment. We model root competition for space as an evolutionary game. In response to nutrient competition between plants, an individual's optimal strategy (the spatial distribution of root proliferation) depends on the rooting strategies of neighbouring plants. The model defines and predicts the fundamental (in the absence of competition) and realized (in the presence of competition) root space of an individual plant. Overlapping fundamental root spaces guarantee smaller, yet still overlapping, realized root spaces as individuals concede some but not all space to a neighbour's roots. Root overlap becomes an intentional consequence of the neighbouring plants playing a nutrient foraging game. Root proliferation and regions of root overlap should increase with soil fertility, decline with the distance cost of root production (e.g. soil compactness) and shift with competitive asymmetries. Seemingly erratic patterns of root proliferation and root overlap become the expected outcome of nutrient foraging games played in soils with small-scale heterogeneities in nutrient availability. PMID:17251098

  10. Root proliferation and seed yield in response to spatial heterogeneity of below-ground competition.

    Science.gov (United States)

    O'Brien, Erin E; Gersani, Mordechai; Brown, Joel S

    2005-11-01

    Here, we tested the predictions of a 'tragedy of the commons' model of below-ground plant competition in annual plants that experience spatial heterogeneity in their competitive environment. Under interplant competition, the model predicts that a plant should over-proliferate roots relative to what would maximize the collective yield of the plants. We predict that a plant will tailor its root proliferation to local patch conditions, restraining root production when alone and over-proliferating in the presence of other plants. A series of experiments were conducted using pairs of pea (Pisum sativum) plants occupying two or three pots in which the presence or absence of interplant root competition was varied while nutrient availability per plant was held constant. In two-pot experiments, competing plants produced more root mass and less pod mass per individual than plants grown in isolation. In three-pot experiments, peas modulated this response to conditions at the scale of individual pots. Root proliferation in the shared pot was higher compared with the exclusively occupied pot. Plants appear to display sophisticated nutrient foraging with outcomes that permit insights into interplant competition.

  11. Cascading effects of belowground predators on plant communities are density-dependent.

    Science.gov (United States)

    Thakur, Madhav Prakash; Herrmann, Martina; Steinauer, Katja; Rennoch, Saskia; Cesarz, Simone; Eisenhauer, Nico

    2015-10-01

    interspecific plant competition. These results highlight that belowground predators can relax interspecific plant competition by increasing nutrient mineralization through their density-dependent cascading effects on detritivore and soil microbial communities. PMID:26664680

  12. 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

    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...... and Trichospermum mexicanum, two pioneer species that dominate the secondary forests in the study region, varied with the abundance and size of neighboring trees in 1-2 year old secondary vegetation. We found that local neighborhood basal area varied 10-fold (3 to 30 cm(2) m(-2)) and explained most of the variation...... on the diameter growth of Cecropia saplings and stem slenderness of Trichospermum saplings. We conclude that competition for light was more important than below-ground competition in this initial phase of moist tropical forest successional, despite the low soil fertility....

  13. 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.

  14. 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.

  15. 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

  16. Nitrogen Addition Altered the Effect of Belowground C Allocation on Soil Respiration in a Subtropical Forest.

    Science.gov (United States)

    He, Tongxin; Wang, Qingkui; Wang, Silong; Zhang, Fangyue

    2016-01-01

    The availabilities of carbon (C) and nitrogen (N) in soil play an important role in soil carbon dioxide (CO2) emission. However, the variation in the soil respiration (Rs) and response of microbial community to the combined changes in belowground C and N inputs in forest ecosystems are not yet fully understood. Stem girdling and N addition were performed in this study to evaluate the effects of C supply and N availability on Rs and soil microbial community in a subtropical forest. The trees were girdled on 1 July 2012. Rs was monitored from July 2012 to November 2013, and soil microbial community composition was also examined by phospholipid fatty acids (PLFAs) 1 year after girdling. Results showed that Rs decreased by 40.5% with girdling alone, but N addition only did not change Rs. Interestingly, Rs decreased by 62.7% under the girdling with N addition treatment. The reducing effect of girdling and N addition on Rs differed between dormant and growing seasons. Girdling alone reduced Rs by 33.9% in the dormant season and 54.8% in the growing season compared with the control. By contrast, girdling with N addition decreased Rs by 59.5% in the dormant season and 65.4% in the growing season. Girdling and N addition significantly decreased the total and bacterial PLFAs. Moreover, the effect of N addition was greater than girdling. Both girdling and N addition treatments separated the microbial groups on the basis of the first principal component through principal component analysis compared with control. This indicated that girdling and N addition changed the soil microbial community composition. However, the effect of girdling with N addition treatment separated the microbial groups on the basis of the second principal component compared to N addition treatment, which suggested N addition altered the effect of girdling on soil microbial community composition. These results suggest that the increase in soil N availability by N deposition alters the effect of

  17. Effects of Manipulated Above- and Belowground Organic Matter Input on Soil Respiration in a Chinese Pine Plantation

    OpenAIRE

    Juan Fan; Jinsong Wang; Bo Zhao; Lianhai Wu; Chunyu Zhang; Xiuhai Zhao; 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 a...

  18. 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.

  19. Effects of long-term grazing disturbance on the belowground storage of organic carbon in the Patagonian Monte, Argentina.

    Science.gov (United States)

    Larreguy, C; Carrera, A L; Bertiller, M B

    2014-02-15

    The objective of this study was to analyze the effect of grazing disturbance on the amount and the spatial distribution (vertical and horizontal) of root biomass and soil organic carbon (SOC) in order to evaluate whether grazing alters the belowground storage of organic carbon (C) in arid rangelands of the Patagonian Monte. We selected three representative sites (3 ha each) with low, moderate and high grazing disturbance located far, mid-distance and near the watering point, respectively, in rangelands submitted to sheep grazing for more than 100 years. We assessed the canopy structure and identified the four most frequent plant patch types at each site. We selected four replications of each patch type and extracted a soil sample (0-30 cm depth) underneath the canopy and in the middle of the nearest inter-patch bare soil area in winter and summer. We assessed the root and soil dry mass and the respective organic C concentration in each sample and then we estimated the total belowground organic C storage at each site. Total plant and perennial grass cover were lower with high than low grazing disturbance while the reverse occurred with dwarf shrub cover. High grazing disturbance led to the increase in total root biomass in the whole soil profile of patch areas and in the upper soil of inter-patch areas. SOC was higher in patch than in inter-patch areas at all sites but at both areas was reduced with high grazing disturbance. This was probably the result of the low total plant cover and the low and recalcitrant contribution of above and below-ground plant litter to soils at sites with high grazing disturbance. Accordingly, these changes did not result in variations in the total belowground organic C storage. We concluded that high grazing disturbance did not affect the total belowground organic C storage but led to changes in the spatial patterning of this organic C storage (i.e shifting from soil to roots).

  20. 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 divers

  1. Competition Effects of Supermarket Services

    OpenAIRE

    Bonanno, Alessandro; Lopez, Rigoberto A.

    2007-01-01

    This paper investigates the effect of in-store services on retail food prices, supermarket competition, and demand using fluid milk as a case study. It is shown that higher-service supermarkets charge higher milk prices essentially because of an increase in market power due to differentiation of service offering. Results show that different types of services impact milk prices differently, that upscale food-retailers face stronger competition in newer services, and that service competition re...

  2. 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

    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......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....... Overall, we found a significant effect of reduced soil N availability on aboveground biomass and belowground plant biomass production. Specifically, responses of aboveground and belowground community biomass to nutrients were driven by reductions in soil N, but not additions, indicating that soil N may...

  3. Explaining competitive reaction effects

    NARCIS (Netherlands)

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

    2001-01-01

    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 re

  4. Simulated Sea-Level Rise Effects on the Above and Below-Ground Growth of Two Tidal Marsh Plant Species

    Science.gov (United States)

    Schile, L. M.; Callaway, J. C.; Kelly, M.

    2011-12-01

    Sea-level is expected to rise between 55 and 140 cm in the next century and is likely to have significant effects on the distribution and maintenance of tidal wetlands; however, little is known about the effects of increased sea level on Pacific coast tidal marsh vegetation. We initiated a field experiment in March 2011 to examine how increased depth and duration of inundation affect above and below-ground growth of two tidal wetland plant species: Schoenoplectus acutus and S. americanus. PVC planters, referred to as marsh organs, were installed at fixed elevations in channels at two ancient marshes in the San Francisco Bay Estuary: Browns Island and Rush Ranch. Each marsh organ structure is comprised of five rows of three six-inch PVC pipes, with each row 15cm lower than the row above, and was filled with surrounding mudflat sediment. Elevations span 60 cm and were chosen to be lower than the average current elevations of both species at each marsh to reflect projected increases in sea level. Rhizomes were collected from Browns Island, the less-saline site, and were cut to uniform sizes before planting. In every row, each species was grown individually and together. On a monthly basis, plant heights were recorded and pore-water sulfide concentration, salinity, and soil oxidation-reduction potential were measured. Schoenoplectus americanus growth and density significantly decreased with increased inundation at both sites. Schoenoplectus acutus growth was impacted more significantly at lower elevations at Rush Ranch but had little variation in density and growth across elevations at Browns Island. Salinity and sulfide concentrations varied little across elevations within a site but differed between sites. Above and belowground biomass will be collected in September 2011 to measure total annual productivity. The experiment provides basic yet crucial information on the impacts of increased inundation on tidal wetland vegetation and insight into potential changes in

  5. The Effects of Tax Competition

    Directory of Open Access Journals (Sweden)

    Ioan TALPOŞ

    2010-08-01

    Full Text Available Tax competition between governments is a research topic of growing importance in the context of globalization. This subject is particularly important for the European Union, characterized by a high degree of economic integration, single currency and free movement of goods, services, persons and capital. In this paper we define the concept of tax competition and we provide a review of the literature to highlight its potential effects.

  6. The Effects of Tax Competition

    OpenAIRE

    Ioan TALPOŞ; Alexandru O. CRÂŞNEAC

    2010-01-01

    Tax competition between governments is a research topic of growing importance in the context of globalization. This subject is particularly important for the European Union, characterized by a high degree of economic integration, single currency and free movement of goods, services, persons and capital. In this paper we define the concept of tax competition and we provide a review of the literature to highlight its potential effects.

  7. Effects of elevated pO3 on carbon cycle between above and belowground organs of trees

    Institute of Scientific and Technical Information of China (English)

    LIU Xi-ping; Rennenberg Heinz; Matyssek Rainer

    2006-01-01

    Translocation of carbohydrate from leaves to roots via phloem and reallocation from roots to leaves via xylem regulate the allocation of carbon (C) between above and belowground organs of trees. To quantitatively analyze effects of elevated ozone concentrations pO3 on the internal cycle of C, juvenile beech and spruce were grown in phytotrons and exposed to ambient and elevated pO3 (i.e. twice-ambient O3 levels, restricted to < 150 ppb) for two growing seasons. The translocation of C in the phloem and xylem was quantitatively studied by investigating the phloem/xylem-loading of sugars, the differentiation of stem conductive tissue and the hourly water flow through the stem. Results in the present study shown, elevated pO3 significantly decreased C translocation from shoot to roots in beech by reducing both sugar concentration in the phloem and conductive phloem area. Elevated pO3 also significantly decreased C reallocation from the roots to the shoot in beech by reducing both of sugar concentration in the xylem and transpiration rate. The adverse effects of elevated pO3 on C translocation in the phloem and xylem, however, were small in spruce.Contrasting to beech, spruce is less sensitive to elevated pO3, regarding to phloem differentiation and sugar concentrations in the phloem and xylem.

  8. 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.

  9. Belowground biodiversity and ecosystem functioning

    NARCIS (Netherlands)

    Bardgett, R.D.; Putten, van der W.H.

    2014-01-01

    Evidence is mounting that the immense diversity of microorganisms and animals that live belowground contributes significantly to shaping aboveground biodiversity and the functioning of terrestrial ecosystems. Our understanding of how this belowground biodiversity is distributed, and how it regulates

  10. Above- and below-ground herbivory effects on below-ground plant–fungus interactions and plant–soil feedback responses

    NARCIS (Netherlands)

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

    2013-01-01

    Summary Feeding by insect herbivores can affect plant growth and the concentration of defense compounds in plant tissues. Since plants provide resources for soil organisms, herbivory can also influence the composition of the soil community via its effects on the plant. Soil organisms, in turn, are i

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

    Directory of Open Access Journals (Sweden)

    Juan Fan

    Full Text Available 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.

  12. 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. PMID:25970791

  13. Exploring the Competitive Effects of Charter Schools

    Science.gov (United States)

    Carpenter, Dick M., II; Medina, Paul M.

    2011-01-01

    Central to the debate over school choice has been the question of how public schools respond to market-based competition. Many choice advocates suggest that competition can spur public schools to become more effective and efficient, but the evidence regarding the effect of competition from charters is comparably sparse and mixed. This article…

  14. Above- and below-ground effects of plant diversity depend on species origin

    DEFF Research Database (Denmark)

    Kuebbing, Sara E.; Classen, Aimee Taylor; Sanders, Nate;

    2015-01-01

    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...

  15. 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.

  16. Competition

    OpenAIRE

    Boone, J.

    2000-01-01

    Competition has been modelled in the literature in a number of ways.What do these different parametrizations of competition have in common?For instance, it turns out that it is not always the case that a rise in competition reduces price cost margins, industry wide profits or concentration.All parametrizations of competition, considered here, have two features in common.First, the reallocation effect: a rise in competition raises the profits of a firm relative to the profits of a less efficie...

  17. Interactive effects of belowground organic matter input, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

    Directory of Open Access Journals (Sweden)

    L. N. Ma

    2013-06-01

    Full Text Available Soil organic matter (SOM inputs, increased precipitation and clipping (reducing belowground photosynthates allocation are predicted to affect soil C and N cycling in temperate grassland ecosystems. However, the interactive effects between SOM inputs (or increased precipitation and clipping on soil C and N mineralization in temperate steppes are still poorly understood. A field manipulation experiment was conducted to quantify the effects of SOM inputs, increased precipitation, clipping and their interactions on soil C and N mineralization in a temperate steppe of northeastern China from 2010 to 2011. The results showed that SOM inputs significantly increased soil C mineralization rate (CMR and net N mineralization rate (NMR. Increased precipitation-induced enhancement of soil CMR essentially ceased after the first year, stimulation of soil NMR and NNR continued into the second year. However, clipping only marginally decreased soil CMR and NMR during the two years. There were significant synergistic interactions between SOM inputs (or increased precipitation and clipping on soil CMR and NMR, as SOM inputs (or increased precipitation showed greater effects on soil CMR and NMR under clipped plots than under unclipped plots, which could be explained by the relative shifts in soil microbial community structure because of bacterial biomass increases, and by the relative decreases in arbuscular mycorrhizal fungi biomass due to the reduction of belowground photosynthates allocation. These results highlight the importance of plants in mediating the responses of soil C and N mineralization to potentially increased SOM and precipitation by controlling belowground photosynthates allocation in the temperate steppe. Thus, the findings have important implications for improving prediction of C and N sequestration potential and its feedbacks to climate change in temperate steppe ecosystems.

  18. Linking aboveground and belowground diversity

    NARCIS (Netherlands)

    Deyn, de G.B.; Putten, van der W.H.

    2005-01-01

    Aboveground and belowground species interactions drive ecosystem properties at the local scale, but it is unclear how these relationships scale-up to regional and global scales. Here, we discuss our current knowledge of aboveground and belowground diversity links from a global to a local scale. Glob

  19. The Unintended Effects of Private School Competition

    DEFF Research Database (Denmark)

    Andersen, Simon Calmar; Serritzlew, Søren

    2007-01-01

    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...... 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...

  20. 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...... 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...

  1. Competition-density effect in plant populations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The competition-density effect of plant populations is of significance in theory and practice of forest management and has been studied for long time. The differences between the two reciprocal equations of the competition-density effect in nonself-thinning populations and self-thinning populations were analyzed theoretically. This supplies a theoretical basis for analyzing the dynamics of forest populations and evaluating the effect of forest management.

  2. When CO2 kills: effects of magmatic CO2 flux on belowground biota at Mammoth Mountain, CA

    Science.gov (United States)

    McFarland, J.; Waldrop, M. P.; Mangan, M.

    2011-12-01

    The biomass, composition, and activity of the soil microbial community is tightly linked to the composition of the aboveground plant community. Microorganisms in aerobic surface soils, both free-living and plant-associated are largely structured by the availability of growth limiting carbon (C) substrates derived from plant inputs. When C availability declines following a catastrophic event such as the death of large swaths of trees, the number and composition of microorganisms in soil would be expected to decline and/or shift to unique microorganisms that have better survival strategies under starvation conditions. High concentrations of volcanic cold CO2 emanating from Mammoth Mountain near Horseshoe Lake on the southwestern edge of Long Valley Caldera, CA has resulted in a large kill zone of tree species, and associated soil microbial species. In July 2010, we assessed belowground microbial community structure in response to disturbance of the plant community along a gradient of soil CO2 concentrations grading from 80% (no plant life). We employed a microbial community fingerprinting technique (automated ribosomal intergenic spacer analysis) to determine changes in overall community composition for three broad functional groups: fungi, bacteria, and archaea. To evaluate changes in ectomycorrhizal fungal associates along the CO2 gradient, we harvested root tips from lodgepole pine seedlings collected in unaffected forest as well as at the leading edge of colonization into the kill zone. We also measured soil C fractions (dissolved organic C, microbial biomass C, and non-extractable C) at 10 and 30 cm depth, as well as NH4+. Not surprisingly, our results indicate a precipitous decline in soil C, and microbial C with increasing soil CO2; phospholipid fatty acid analysis in conjunction with community fingerprinting indicate both a loss of fungal diversity as well as a dramatic decrease in biomass as one proceeds further into the kill zone. This observation was

  3. Interspecific resource competition effects on fisheries revenue.

    Directory of Open Access Journals (Sweden)

    Karen E van de Wolfshaar

    Full Text Available 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 dynamics and revenue of simultaneously harvested species has received little attention due to the historical single stock approach in fisheries management. Here we present the results of a modelling study on the interaction between resource competition of sole (Solea solea and slaice (Pleuronectus platessa and simultaneous harvesting of these species, using a stage-structured population model. Three resources were included of which one is shared with a varied competition intensity. We find that plaice is the better competitor of the two species and adult plaice are more abundant than adult sole. When competition is high sole population biomass increases with increasing fishing effort prior to plaice extinction. As a result of this increase in the sole population, the revenue of the stocks combined as function of effort becomes bimodal with increasing resource competition. When considering a single stock quota for sole, its recovery with increasing effort may result in even more fishing effort that would drive the plaice population to extinction. When sole and plaice compete for resources the highest revenue is obtained at effort levels at which plaice is extinct. Ignoring resource competition promotes overfishing due to increasing stock of one species prior to extinction of the other species. Consequently, efforts to mitigate the decline in one species will not be effective if increased stock in the other species leads to increased quota. If a species is to be protected against extinction, management should not only be directed at this one species, but all species that compete with it for resource as well.

  4. Placebo effects in competitive sport: qualitative data.

    Science.gov (United States)

    Beedie, Christopher J

    2007-01-01

    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. Key pointsA survey of 30 athletes revealed that 73% have experienced a placebo effect in sport.Athletes suggest several potential explanations for these effects.Findings support the idea that placebo effects might be common in sport.Researchers and practitioners should be aware of the possible impact of these effects on research findings and competitive performance.

  5. Creating Competitive Advantage through Effective Management Education.

    Science.gov (United States)

    Longenecker, Clinton O.; Ariss, Sonny S.

    2002-01-01

    Managers trained in executive education programs (n=203) identified ways in which management education can increase an organization's competitive advantage: exposure to new ideas and practices, skill development, and motivation. Characteristics of effective management education included experience-based learning orientation, credible instructors,…

  6. 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

  7. EFFECTIVE INCENTIVES AND CHICKPEA COMPETITIVENESS IN INDIA

    OpenAIRE

    Rao, Krishna D.; Kyle, Steven C.

    1997-01-01

    This paper attempts to measure the impact of government intervention in product and factor markets on chickpea competitiveness in India. This is done by estimating the nominal (NPC), effective (EPC) and effective subsidy (ESC) protection coefficients for chickpea and its main competing crops -wheat and mustard. Further, the Net Economic Benefit (NEB) in the production of these three crops is estimated to indicate where comparative advantage and production efficiency in production lie. In addi...

  8. 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…

  9. When competition breeds equality: effects of appetitive versus aversive competition in negotiation

    NARCIS (Netherlands)

    F.S. ten Velden; B. Beersma; C.K.W. de Dreu

    2011-01-01

    Competitive motivation is prevalent in negotiation but systematic insight into its effects is missing. We introduce the distinction between appetitive competition, in which negotiators seek relative gain, and aversive competition, in which negotiators seek to prevent relative loss. Two experiments t

  10. Competition

    NARCIS (Netherlands)

    Boone, J.

    2000-01-01

    Competition has been modelled in the literature in a number of ways.What do these different parametrizations of competition have in common?For instance, it turns out that it is not always the case that a rise in competition reduces price cost margins, industry wide profits or concentration.All param

  11. Decadal Effects of Elevated CO2 and O3 on Forest Soil Respiration and Belowground Carbon Cycling at Aspen FACE

    Science.gov (United States)

    Talhelm, A. F.; Pregitzer, K. S.; Zak, D. R.; Burton, A. J.

    2014-12-01

    Three northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2) and/or tropospheric ozone (O3) for 11 years, advancing from open-grown seedlings 8 m tall. Here, we report results from measurements of soil respiration that occurred during the experiment from 1999 to 2008. In order to better understand this flux, we compare changes in soil respiration to the effects of CO2 and O3 on net primary productivity (NPP), fine root biomass, and leaf litter production. Elevated CO2 enhanced soil respiration by an average of 28%. This stimulation of soil respiration varied from +19% to +44%, but did not change consistently during the 10 year measurement period (r2 = 0.04). The effect of elevated O3 on soil respiration was dynamic. In year two of the experiment (1999), elevated O3 decreased soil respiration by 7%. However, soil respiration consistently increased through time under elevated O3 (r2 = 0.71) and was 9% greater than under ambient O3 in the final year of the experiment (2008). Overall, elevated O3 had no meaningful effect on soil respiration (+0.3%). The annual effects of elevated CO2 on soil respiration were not correlated with NPP or fine root biomass, but was positively correlated with leaf litter production (r = 0.57). Annual leaf litter production was also related to the annual effects of elevated O3 on soil respiration (r = 0.78), but relationship was tighter between annual O3 effects on NPP and soil respiration (r = 0.83).

  12. Above- and below-ground herbivory effects on below- ground plant-fungus interactions and plant-soil feedback responses

    NARCIS (Netherlands)

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

    2013-01-01

    1.Feeding by insect herbivores can affect plant growth and the concentration of defense compounds in plant tissues. Since plants provide resources for soil organisms, herbivory can also influence the composition of the soil community via its effects on the plant. Soil organisms, in turn, are importa

  13. 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....

  14. Measuring the economic effects of competition law enforcement

    NARCIS (Netherlands)

    Don, H.; Kemp, R.G.M.; Sinderen, J.

    2008-01-01

    Together with a move from a rules-based legal approach to a more economic approach in competition cases, the economic effects of competition law enforcement have received increasing attention. Measuring these effects is important for external accountability of the Competition Authority, for quality

  15. Competition.

    Science.gov (United States)

    Chambers, D W

    1997-01-01

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

  16. Competition in the Sandbox: A Test of the Effects of Preschool Competition on Educational Outcomes

    Science.gov (United States)

    Henry, Gary T.; Gordon, Craig S.

    2006-01-01

    The emergence of publicly subsidized preschool raises important policy questions about the role of market forces and, in places where competition to provide these services exists, presents a setting in which the effects of competition on educational outcomes can be tested. We test neo-institutional hypotheses concerning the effects of competition…

  17. 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

  18. Synergetic effect of benchmarking competitive advantages

    Directory of Open Access Journals (Sweden)

    N.P. Tkachova

    2011-12-01

    Full Text Available It is analyzed the essence of synergistic competitive benchmarking. The classification of types of synergies is developed. It is determined the sources of synergies in conducting benchmarking of competitive advantages. It is proposed methodological framework definition of synergy in the formation of competitive advantage.

  19. Plasticity in above- and belowground resource acquisition traits in response to single and multiple environmental factors in three tree species.

    Science.gov (United States)

    Freschet, Grégoire T; Bellingham, Peter J; Lyver, Philip O'B; Bonner, Karen I; Wardle, David A

    2013-04-01

    Functional trait plasticity is a major component of plant adjustment to environmental stresses. Here, we explore how multiple local environmental gradients in resources required by plants (light, water, and nutrients) and soil disturbance together influence the direction and amplitude of intraspecific changes in leaf and fine root traits that facilitate capture of these resources. We measured population-level analogous above- and belowground traits related to resource acquisition, i.e. "specific leaf area"-"specific root length" (SLA-SRL), and leaf and root N, P, and dry matter content (DMC), on three dominant understory tree species with contrasting carbon and nutrient economics across 15 plots in a temperate forest influenced by burrowing seabirds. We observed similar responses of the three species to the same single environmental influences, but partially species-specific responses to combinations of influences. The strength of intraspecific above- and belowground trait responses appeared unrelated to species resource acquisition strategy. Finally, most analogous leaf and root traits (SLA vs. SRL, and leaf versus root P and DMC) were controlled by contrasting environmental influences. The decoupled responses of above- and belowground traits to these multiple environmental factors together with partially species-specific adjustments suggest complex responses of plant communities to environmental changes, and potentially contrasting feedbacks of plant traits with ecosystem properties. We demonstrate that despite the growing evidence for broadly consistent resource-acquisition strategies at the whole plant level among species, plants also show partially decoupled, finely tuned strategies between above- and belowground parts at the intraspecific level in response to their environment. This decoupling within species suggests a need for many species-centred ecological theories on how plants respond to their environments (e.g. competitive/stress-tolerant/ruderal and

  20. Competition

    NARCIS (Netherlands)

    F. Bridoux

    2014-01-01

    Competition traditionally refers to the actions that firms take in a product market to outperform rivals in attracting customers and generating revenues. Yet, competition extends beyond product markets to other arenas such as factor markets, where firms compete for resources, and the political arena

  1. Competition

    Institute of Scientific and Technical Information of China (English)

    吕思思

    2007-01-01

    <正> The term competition reminds me of asoul-stirring fight between a mother monkeyand a crocodile,The crocodile caught her babywhen the baby was drinking water in a pool,Inthe end,the mother got her baby,but herbaby’s body only,She lost her child forever,just for a mouthful of water.Such is competition,cruel and merciless,But if we see the other side of the coin,we’ll

  2. Competitiveness

    Science.gov (United States)

    Minihan, Charles E.

    1991-03-01

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

  3. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from -20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass-temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  4. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from ‑20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass–temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  5. Plant functional traits have globally consistent effects on competition.

    Science.gov (United States)

    Kunstler, Georges; Falster, Daniel; Coomes, David A; Hui, Francis; Kooyman, Robert M; Laughlin, Daniel C; Poorter, Lourens; Vanderwel, Mark; Vieilledent, Ghislain; Wright, S Joseph; Aiba, Masahiro; Baraloto, Christopher; Caspersen, John; Cornelissen, J Hans C; Gourlet-Fleury, Sylvie; Hanewinkel, Marc; Herault, Bruno; Kattge, Jens; Kurokawa, Hiroko; Onoda, Yusuke; Peñuelas, Josep; Poorter, Hendrik; Uriarte, Maria; Richardson, Sarah; Ruiz-Benito, Paloma; Sun, I-Fang; Ståhl, Göran; Swenson, Nathan G; Thompson, Jill; Westerlund, Bertil; Wirth, Christian; Zavala, Miguel A; Zeng, Hongcheng; Zimmerman, Jess K; Zimmermann, Niklaus E; Westoby, Mark

    2016-01-14

    Phenotypic traits and their associated trade-offs have been shown to have globally consistent effects on individual plant physiological functions, but how these effects scale up to influence competition, a key driver of community assembly in terrestrial vegetation, has remained unclear. Here we use growth data from more than 3 million trees in over 140,000 plots across the world to show how three key functional traits--wood density, specific leaf area and maximum height--consistently influence competitive interactions. Fast maximum growth of a species was correlated negatively with its wood density in all biomes, and positively with its specific leaf area in most biomes. Low wood density was also correlated with a low ability to tolerate competition and a low competitive effect on neighbours, while high specific leaf area was correlated with a low competitive effect. Thus, traits generate trade-offs between performance with competition versus performance without competition, a fundamental ingredient in the classical hypothesis that the coexistence of plant species is enabled via differentiation in their successional strategies. Competition within species was stronger than between species, but an increase in trait dissimilarity between species had little influence in weakening competition. No benefit of dissimilarity was detected for specific leaf area or wood density, and only a weak benefit for maximum height. Our trait-based approach to modelling competition makes generalization possible across the forest ecosystems of the world and their highly diverse species composition.

  6. 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

    Herbivory is an important modulator of plant biodiversity and productivity in grasslands, but our understanding of herbivore-induced changes on below-ground processes and communities is limited. Using a long-term (17 years) experimental site, we evaluated impacts of rabbit and invertebrate grazers...... between different taxa) were more strongly affected by invertebrate grazers than rabbits. Furthermore, our results suggest that exclusion of invertebrate grazers decreases both microbial biomass and abundance of genes associated with key biogeochemical cycles, and could thus have long-term consequences...... on some soil functions involved in carbon cycling, microbial diversity, structure and functional composition. Both rabbit and invertebrate grazing impacted soil functions and microbial community structure. All functional community measures (functions, biogeochemical cycling genes, network association...

  7. Competition

    CERN Multimedia

    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.

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

    OpenAIRE

    de la Pena, 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 ...

  9. Nutrient subsidies to belowground microbes impact aboveground food web interactions.

    Science.gov (United States)

    Hines, Jes; Megonigal, J Patrick; Denno, Robert F

    2006-06-01

    Historically, terrestrial food web theory has been compartmentalized into interactions among aboveground or belowground communities. In this study we took a more synthetic approach to understanding food web interactions by simultaneously examining four trophic levels and investigating how nutrient (nitrogen and carbon) and detrital subsidies impact the ability of the belowground microbial community to alter the abundance of aboveground arthropods (herbivores and predators) associated with the intertidal cord grass Spartina alterniflora. We manipulated carbon, nitrogen, and detrital resources in a field experiment and measured decomposition rate, soil nitrogen pools, plant biomass and quality, herbivore density, and arthropod predator abundance. Because carbon subsidies impact plant growth only indirectly (microbial pathways), whereas nitrogen additions both directly (plant uptake) and indirectly (microbial pathways) impact plant primary productivity, we were able to assess the effect of both belowground soil microbes and nutrient availability on aboveground herbivores and their predators. Herbivore density in the field was suppressed by carbon supplements. Carbon addition altered soil microbial dynamics (net potential ammonification, litter decomposition rate, DON [dissolved organic N] concentration), which limited inorganic soil nitrogen availability and reduced plant size as well as predator abundance. Nitrogen addition enhanced herbivore density by increasing plant size and quality directly by increasing inorganic soil nitrogen pools, and indirectly by enhancing microbial nitrification. Detritus adversely affected aboveground herbivores mainly by promoting predator aggregation. To date, the effects of carbon and nitrogen subsidies on salt marshes have been examined as isolated effects on either the aboveground or the belowground community. Our results emphasize the importance of directly addressing the soil microbial community as a factor that influences

  10. Impact of interspecific competition and drought on the allocation of new assimilates in trees.

    Science.gov (United States)

    Hommel, R; Siegwolf, R; Zavadlav, S; Arend, M; Schaub, M; Galiano, L; Haeni, M; Kayler, Z E; Gessler, A

    2016-09-01

    In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure. PMID:27061772

  11. Competition effects in charged particle induced reactions

    International Nuclear Information System (INIS)

    Absolute cross sections have been measured for 14 reactions: 54Cr(p,γ)55Mn for 0.83 MeV less than or equal to E/sub p/ less than or equal to 3.61 MeV, 54Cr(pn,)54Mn for 2.23 MeV less than or equal to E/sub p/ less than or equal to 3.61 MeV, 51V(p,γ)52Cr for 0.93 MeV less than or equal to E/sub p/ less than or equal to 4.47 MeV, 51V(p,n)51Cr for 1.58 MeV 68Zn(p,γ)69Ga for 1.67 MeV less than or equal to E/sub p/ less than or equal to 4.97 MeV, 68Zn(p,n)68Ga for 3.77 MeV less than or equal to E/sub p/ less than or equal to 5.03 MeV, 68Zn(p,γ)65Cu for 3.36 MeV less than or equal to E/sub p/ less than or equal to 5.48 MeV, 48Ca(p,γ)49Sc for 0.58 MeV less than or equal to E/sub p/ less than or equal to 2.67 MeV, 48Ca(p,n,)48Sc for 0.96 less than or equal to E/sub p/ less than or equal to 2.67 MeV, 37Cl(α,γ)41K for 2.90 MeV less than or equal to E/sub α/ less than or equal to 5.23 MeV, 62Ni(α,γ)66Zn for 5.07 MeV less than or equal to E/sub α/ less than or equal to 8.64 MeV, 62Ni(α,n)65Zn for 6.95 MeV less than or equal to E/sub α/ less than or equal to 8.76 MeV, 64Ni(α,γ)68Zn for 4.50 MeV less than or equal to E/sub α/ less than or equal to 7.45 MeV, and 64Ni(α,n)67Zn for 5.29 less than or equal to E/sub α/ less than or equal to 7.44 MeV. Substantial drops in cross section were observed above the neutron thresholds for all the radiative capture reactions except 48Ca(p,γ). In the 48Ca(p,γ)and 68Zn(p,α) reactions significant though smaller neutron competition effects were observed. These cross sections were compared with cross sections calculated with global Hauser-Feshbach models. Criteria for isospin indexing, width fluctuation corrections, and black nuclues strength functions were established

  12. Indirect Effects of Environmental Change in Resource Competition Models.

    Science.gov (United States)

    Kleinhesselink, Andrew R; Adler, Peter B

    2015-12-01

    Anthropogenic environmental change can affect species directly by altering physiological rates or indirectly by changing competitive outcomes. The unknown strength of competition-mediated indirect effects makes it difficult to predict species abundances in the face of ongoing environmental change. Theory developed with phenomenological competition models shows that indirect effects are weak when coexistence is strongly stabilized, but these models lack a mechanistic link between environmental change and species performance. To extend existing theory, we examined the relationship between coexistence and indirect effects in mechanistic resource competition models. We defined environmental change as a change in resource supply points and quantified the resulting competition-mediated indirect effects on species abundances. We found that the magnitude of indirect effects increases in proportion to niche overlap. However, indirect effects also depend on differences in how competitors respond to the change in resource supply, an insight hidden in nonmechanistic models. Our analysis demonstrates the value of using niche overlap to predict the strength of indirect effects and clarifies the types of indirect effects that global change can have on competing species. PMID:26655983

  13. The Effects of Imbalanced Competition on Demonstration Strategies

    OpenAIRE

    Heiman, Amir; Ofir, Chezy

    2010-01-01

    This paper analyzes the effect of competition on product demonstration decisions. Pre-purchase product demonstration enables marketers to differentiate products that are ex-post differentiated but are judged according to perceived fit, rather than actual fit, due to pre-purchase consumer uncertainty. Imbalanced competition accompanied by fit uncertainty motivates the follower to offer demonstrations to avoid a price war. This paper explores the conditions that lead the leader to retaliate. In...

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

    DEFF Research Database (Denmark)

    Kato, Takao; Shu, Pian

    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...... altruistic behaviors....

  15. Competitive energy markets. The effective route to improving the environment

    International Nuclear Information System (INIS)

    Market forces, operating in an increasingly competitive energy market, are a preferred route to achieving environmental and energy efficiency benefits, than those which can be achieved through a managed approach adopted by many governments. It is shown, through examples, how electricity is a catalyst for change at several levels in business, the community and the general economy. Experience in the United Kingdom indicates that free market forces and inter-energy competition not only help improve the regional and therefore national economy, but they offer a very effective way of introducing improvements in energy efficiency and the environment. Governments should establish the framework for competition and regulation but not attempt to manage an industry, which is invariably done more effectively by those who run them. (author)

  16. Competition between triplet superconductivity and Kondo effect

    International Nuclear Information System (INIS)

    The Kondo effect strongly depends on spin and orbital degrees of freedom of Cooper pairs. We focus on the Kondo effect in a px + ipy-wave superconductor with a full energy gap. The numerical renormalization study shows that the ground state is always a spin doublet for a Simp=1/2 local spin and that it is always a spin singlet for Simp=1. The latter is due to uniaxial spin anisotropy of the Cooper pair. We also compare these results with a case of the dx2-y2 + idxy-wave superconductivity having the same energy-gap structure. (author)

  17. Measuring Competitive Effects from School Voucher Programs: A Systematic Review

    Science.gov (United States)

    Egalite, Anna J.

    2013-01-01

    Studies of the competition effects from voucher or tuition tax credit scholarship programs on public school student academic outcomes have taken place in seven locations throughout the United States, with the majority of studies taking place in Florida, followed by Wisconsin. This article reviews 21 total studies of the impacts on student academic…

  18. Review of Information Technology Effect on Competitive Advantage- Strategic Perspective

    Directory of Open Access Journals (Sweden)

    Poolad Daneshvar

    2010-11-01

    Full Text Available Each organisation is aware of the special effects, benefits and implication of Information technology (IT in business performance and also its capacity in building sustainable competitive advantages. In business, IT is used through the value chains of activities which help the organisation to optimize and control functions of operationsfor easy decision making. Also, the use of IT as a competitive weapon has become a popular instrument to influence on a particular organisational performance and the processes that will allow a smooth coordination of technology and corporate as well as business strategies. This article attempts to integrate them in as a more comprehensive viewpoint ,then turns to the major research issues in understanding the impact of information technology on competitive strategy and mention the importance of alignment of IT/IS and business strategies of organisations as a key issue for managers to formulate the organisational business and IT/IS strategies.

  19. Safety in numbers? The effect of network competition on cybersecurity

    OpenAIRE

    Gideon, Carolyn; Hogendorn, Christiaan

    2014-01-01

    Economic incentives for security investment in elements of the Internet is of increasing concern. This paper contains an exploration of the incentives for Internet service providers (ISP)s to invest in security. The analysis focuses on the spillover effects of ISP security investments to other ISPs, which may be serving a different market or competing in the same market. The findings show that the nature of these spillover effects can change the effect competition in the ISP market has on inc...

  20. Bertrand competition in markets with network effects and switching costs

    OpenAIRE

    Suleymanova, Irina; Wey, Christian

    2011-01-01

    We analyze market dynamics under Bertrand duopoly competition in industries with network effects and consumer switching costs. Consumers form installed bases, repeatedly buy the products, and differ with respect to their switching costs. Depending on the ratio of switching costs to network effects, our model generates convergence to monopoly as well as market sharing as equilibrium outcomes. Convergence can be monotone or alternating in both scenarios. A critical mass effect, where consumers ...

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

    OpenAIRE

    D’Ercole, Simonetta; TIERI, Marco; Martinelli, Diego; Tripodi, Domenico

    2016-01-01

    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 In...

  2. Organizational Effectiveness: Social Capital and Competitive Advantage Approach

    Directory of Open Access Journals (Sweden)

    Vini Wiratno Putri

    2016-04-01

    Full Text Available This study is aimed at developing the model of organizational effectiveness in university through social capital and competitive advantage. The populations of this study are the head of study programs and the structural officials in some Universities in Semarang. In this case, We used Structural Equation Modeling (SEM in AMOS 21.0 program as the analysis tool. The result of the study and model analysis showed that even though the social capital had significant positive influenced to the competitive advantage in the university, the improvement of social capital and competitive advantage at university could not improve the university organizational effectiveness. Then, between two factors which influenced the competitive advantage (internal social capital and external social capital, it is obtained that external social capital got the dominant influenced factor to competitive advantage. The managerial implication suggested the policies should focus on improving the quality of cooperative relationships with external parties in the university. Tujuan dari penelitian ini adalah membangun model efektifitas organisasi pada perguruan tinggi melalui modal sosial dan keunggulan bersaing. Populasi dalam penelitian ini adalah ketua program studi maupun pejabat struktural pada perguruan tinggi di Semarang. Alat analisis data yang digunakan adalah Structural Equation Modelling (SEM pada program AMOS 21.0.Hasil pengujian dan analisis model menunjukkan bahwa pada meskipun modal sosial memiliki pengaruh positif signifikan terhadap keunggulan berasingn pada perguruan tinggi namun peningkatan modal sosial dan keunggulan kompetitif pada perguruan tinggi belum mampu meningkatkan efektifitas organidsasi perguruan tinggi tersebut. Selanjutnya diantara kedua faktor yang mempengaruhi keunggulan bersaing (internal social capitaldan external social capital, didapatkan bahwa external social capital merupakan faktor yang paling dominan pengaruhnya terhadap keunggulan

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

    Science.gov (United States)

    D'Ercole, Simonetta; Tieri, Marco; Martinelli, Diego; Tripodi, Domenico

    2016-04-01

    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 (poral infection.

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

    Science.gov (United States)

    D'Ercole, Simonetta; Tieri, Marco; Martinelli, Diego; Tripodi, Domenico

    2016-04-01

    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 (poral infection. PMID:27119757

  5. Diffusion of two brands in competition: Cross-brand effect

    Science.gov (United States)

    Laciana, C. E.; Gual, G.; Kalmus, D.; Oteiza-Aguirre, N.; Rovere, S. L.

    2014-11-01

    We study the equilibrium points of a system of equations corresponding to a Bass based model that describes the diffusion of two brands in competition. To increase the understanding of the effects of the cross-brand parameters, we perform a sensitivity analysis. Finally, we show a comparison with an agent-based model inspired in the Potts model. Conclusions include that both models give the same diffusion curves only when the cross coefficients are not null.

  6. Price Competition and Product Differentiation when Goods have Network Effects

    OpenAIRE

    Conrad, Klaus

    2005-01-01

    The objective of our approach is to develop a model which captures horizontal product differentiation under environmental awareness, product innovation under network effects, and price competition whereby environmentally friendly products are costlier to produce. As an example, we refer to automobile producers, offering cars with a gasoline powered engine and one with a natural gas powered engine. The network of petrol stations provide the complementary good. The fulfilled expectation equilib...

  7. Above- and below-ground impacts of introduced predators in seabird-dominated island ecosystems.

    Science.gov (United States)

    Fukami, Tadashi; Wardle, David A; Bellingham, Peter J; Mulder, Christa P H; Towns, David R; Yeates, Gregor W; Bonner, Karen I; Durrett, Melody S; Grant-Hoffman, Madeline N; Williamson, Wendy M

    2006-12-01

    Predators often exert multi-trophic cascading effects in terrestrial ecosystems. However, how such predation may indirectly impact interactions between above- and below-ground biota is poorly understood, despite the functional importance of these interactions. Comparison of rat-free and rat-invaded offshore islands in New Zealand revealed that predation of seabirds by introduced rats reduced forest soil fertility by disrupting sea-to-land nutrient transport by seabirds, and that fertility reduction in turn led to wide-ranging cascading effects on belowground organisms and the ecosystem processes they drive. Our data further suggest that some effects on the belowground food web were attributable to changes in aboveground plant nutrients and biomass, which were themselves related to reduced soil disturbance and fertility on invaded islands. These results demonstrate that, by disrupting across-ecosystem nutrient subsidies, predators can indirectly induce strong shifts in both above- and below-ground biota via multiple pathways, and in doing so, act as major ecosystem drivers. PMID:17118004

  8. 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.

  9. Below-ground effects of enhanced tropospheric ozone and drought in a beech/spruce forest (Fagus sylvatica L. / Picea abies [L.] Karst)

    Science.gov (United States)

    The effects of experimentally elevated O3 on soil respiration rates, standing fine-root biomass, fine-root production and δ13C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with cont...

  10. Disentangling direct and indirect effects of water table drawdown on above and belowground plant litter decomposition: Consequences for accumulation of organic matter in boreal peatlands.

    OpenAIRE

    Strakova, Petra; PenttilÀ, Timo; Laine, Jukka; Laiho, Raija

    2012-01-01

    Pristine peatlands are carbon (C) accumulating wetland ecosystems sustained by a high water table (WT) and consequent anoxia that slows down decomposition. Persistent WT drawdown as a response to climate and/or land-use change affects decomposition either directly through environmental factors such as increased oxygenation, or indirectly through changes in plant community composition. This study attempts to disentangle the direct and indirect effects of WT drawdown by measuring the relative i...

  11. The effect of fertilization on the below-ground diversity and community composition of ectomycorrhizal fungi associated with western hemlock (Tsuga heterophylla).

    Science.gov (United States)

    Wright, Shannon H A; Berch, Shannon M; Berbee, Mary L

    2009-04-01

    Fertilization typically reduces ectomycorrhizal diversity shortly after its application but less is known about its longer-term influence on fungal species. Long-term effects are important in forests where fertilizer is rarely applied. We compared fungal species composition in western hemlock control plots with plots last fertilized 7 years ago with nitrogen (N) or nitrogen plus phosphorus (N + P). The N + P fertilization had a significant lingering effect, increasing the tree size and foliar P content of the western hemlocks. From ectomycorrhizal roots of 24-year-old trees from northern Vancouver Island, Canada, we identified fungi from 12 samples per treatment, by amplifying, cloning, and sequencing fungal ribosomal DNA fragments, placing sequences with 97% or more identity in the same operational taxonomic unit (OTU). Diversity was high across treatments; we detected 77 fungal OTUs, 52 from ectomycorrhizal genera, among 922 clone sequences. The five most frequent OTUs were similar in abundance across treatments. Only 19 OTUs matched any of the 197 previously reported ectomycorrhizal species of western hemlock. Species composition but not diversity in nitrogen plus phosphorus plots differed significantly from control or nitrogen plots. Two Cortinarius OTUs were indicator species for nitrogen plus phosphorus plots and presence of Cortinarius cinnamomeus was correlated with control or nitrogen plots. After 7 years, fertilization history had made no detectable difference in ectomycorrhizal fungal diversity, but long-lasting changes in environment resulting from fertilization had a lingering effect on fungal ectomycorrhizal species composition. PMID:19139932

  12. Carryover effects drive competitive dominance in spatially structured environments.

    Science.gov (United States)

    Van Allen, Benjamin G; Rudolf, Volker H W

    2016-06-21

    Understanding how changes to the quality of habitat patches affect the distribution of species across the whole landscape is critical in our human-dominated world and changing climate. Although patterns of species' abundances across a landscape are clearly influenced by dispersal among habitats and local species interactions, little is known about how the identity and origin of dispersers affect these patterns. Because traits of individuals are altered by experiences in their natal habitat, differences in the natal habitat of dispersers can carry over when individuals disperse to new habitats and alter their fitness and interactions with other species. We manipulated the presence or absence of such carried-over natal habitat effects for up to eight generations to examine their influence on two interacting species across multiple dispersal rates and different habitat compositions. We found that experimentally accounting for the natal habitat of dispersers significantly influenced competitive outcomes at all spatial scales and increased total community biomass within a landscape. However, the direction and magnitude of the impact of natal habitat effects was dependent upon landscape type and dispersal rate. Interestingly, effects of natal habitats increased the difference between species performance across the landscape, suggesting that natal habitat effects could alter competitive interactions to promote spatial coexistence. Given that heterogeneity in habitat quality is ubiquitous in nature, natal habitat effects are likely important drivers of spatial community structure and could promote variation in species performance, which may help facilitate spatial coexistence. The results have important implications for conservation and invasive species management. PMID:27298356

  13. Elevated atmospheric CO sub 2 effects on belowground processes in C sub 3 and C sub 4 estuarine marsh communities. [S. Spartina

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, P.S.; Balduman, L.M.; Drake, B.G.; Whigham, D.F. (Smithsonian Environmental Research Center, Edgewater, MD (USA))

    1990-10-01

    Belowgound carbon allocation is a major component of a plant's carbon budget, yet relatively little is known about the response of roots to elevated atmospheric CO{sub 2}. We have exposed three brackish marsh communities dominated by perennial macrophytes to twice ambient CO{sub 2} concentrations for two full growing seasons using open top chambers. One community was dominated by the C{sub 3} sedge Scirpus olneyi, one was dominated by the C{sub 4} grass Spartina patens, and one was a mixture of S. olneyi, S. patens, and Distichlis spicata, a C{sub 4} grass. Root and rhizome growth were studied in the 2nd yr of exposure by measuring growth into peat cores previously excavated and refilled with sphagnum peat devoid of roots. Growth under elevated CO{sub 2} resulted in an 83% increase in root dry mass per core in the Scirpus community. Those roots were also significantly lower in percentage of nitrogen than roots from ambient-grown plants. There was no effect of elevated CO{sub 2} on root growth or nitrogen content in the Spartina community or in the C{sub 4} component of the Mixed community.

  14. The Effect of Competitive Balance on the Demand for International Cricket

    OpenAIRE

    Sacheti, Abhinav

    2006-01-01

    The issue of competitive balance and its effect on the attendance demand for sport has been covered extensively for many professional sports, but there is very little coverage of the effect of competitive balance on demand for international cricket, particularly in terms of long run competitive balance. This dissertation uses economic analysis to investigate the effect of long run competitive balance on attendance demand for international cricket, using attendance data for Test and one-day in...

  15. 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.

  16. Effects of competition on endurance performance and the underlying psychological and physiological mechanisms.

    Science.gov (United States)

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

    2011-03-01

    Competition can influence performance, however, the underlying psychological and physiological mechanisms are poorly understood. To address this issue we tested mechanisms underlying the competition-performance relationship. Measures of anxiety, effort, enjoyment, autonomic activity and muscle activity were obtained from 94 participants during a handgrip endurance task completed in individual and competition conditions. Competition improved endurance performance, increased anxiety, effort, enjoyment, heart rate and muscle activity, and decreased heart rate variability, R-wave to pulse interval and pulse amplitude. Enjoyment fully mediated whereas effort and heart rate variability partially mediated the effects of competition on performance. In addition, anxiety moderated the competition-performance relationship; those with lower anxiety performed better in competition. We confirm that competition elicits effects on performance through psychological and physiological pathways, and identify mechanisms that underlie improved endurance performance during competition. PMID:21295108

  17. Effects of Phenibut and Citrocard on Non-Competitive and Competitive Behavior during Provoked Aggression in Animals.

    Science.gov (United States)

    Bagmetova, V V; Krivitskaya, A N; Tyurenkov, I N

    2015-05-01

    Anti-aggressive effects of phenibut (25 mg/kg) and its structural analogue citrocard (50 mg/kg) were revealed in rats under condition of provoked intraspecific aggression. These substances significantly decreased manifestations of aggression in animals: they increased the latency of attacks and reduced their number. Anti-aggressive effects of citrocard were more pronounced than effects of phenibut under conditions of non-competitive aggression induced by fear of inescapable painful exposure or under conditions of competitive aggression reflecting the ability of animals to reveal adaptive social communicative skills in aversive situation.

  18. Effects of Phenibut and Citrocard on Non-Competitive and Competitive Behavior during Provoked Aggression in Animals.

    Science.gov (United States)

    Bagmetova, V V; Krivitskaya, A N; Tyurenkov, I N

    2015-05-01

    Anti-aggressive effects of phenibut (25 mg/kg) and its structural analogue citrocard (50 mg/kg) were revealed in rats under condition of provoked intraspecific aggression. These substances significantly decreased manifestations of aggression in animals: they increased the latency of attacks and reduced their number. Anti-aggressive effects of citrocard were more pronounced than effects of phenibut under conditions of non-competitive aggression induced by fear of inescapable painful exposure or under conditions of competitive aggression reflecting the ability of animals to reveal adaptive social communicative skills in aversive situation. PMID:26033589

  19. 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...

  20. How generalist herbivores exploit belowground plant diversity in temperate grasslands.

    Science.gov (United States)

    Wallinger, Corinna; Staudacher, Karin; Schallhart, Nikolaus; Mitterrutzner, Evi; Steiner, Eva-Maria; Juen, Anita; Traugott, Michael

    2014-08-01

    Belowground herbivores impact plant performance, thereby inducing changes in plant community composition, which potentially leads to cascading effects onto higher trophic levels and ecosystem processes and productivity. Among soil-living insects, external root-chewing generalist herbivores have the strongest impact on plants. However, the lack of knowledge on their feeding behaviour under field conditions considerably hampers achieving a comprehensive understanding of how they affect plant communities. Here, we address this gap of knowledge by investigating the feeding behaviour of Agriotes click beetle larvae, which are common generalist external root-chewers in temperate grassland soils. Utilizing diagnostic multiplex PCR to assess the larval diet, we examined the seasonal patterns in feeding activity, putative preferences for specific plant taxa, and whether species identity and larval instar affect food choices of the herbivores. Contrary to our hypothesis, most of the larvae were feeding-active throughout the entire vegetation period, indicating that the grassland plants are subjected to constant belowground feeding pressure. Feeding was selective, with members of Plantaginaceae and Asteraceae being preferred; Apiaceae were avoided. Poaceae, although assumed to be most preferred, had an intermediate position. The food preferences exhibited seasonal changes, indicating a fluctuation in plant traits important for wireworm feeding choice. Species- and instar-specific differences in dietary choice of the Agriotes larvae were small, suggesting that species and larval instars occupy the same trophic niche. According to the current findings, the food choice of these larvae is primarily driven by plant identity, exhibiting seasonal changes. This needs to be considered when analysing soil herbivore-plant interactions. PMID:24188592

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

    Directory of Open Access Journals (Sweden)

    Sean M Watts

    Full Text Available BACKGROUND: 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. METHODOLOGY AND PRINCIPAL FINDINGS: 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. CONCLUSIONS AND SIGNIFICANCE: These results suggest that mainland plants are effective at deterring and tolerating pocket gopher herbivory. Results also suggest

  2. Entry time effects and follow-on drug competition.

    Science.gov (United States)

    Andrade, Luiz Flavio; Sermet, Catherine; Pichetti, Sylvain

    2016-01-01

    Pharmaceutical firms have been criticized for concentrating efforts of R&D on the so-called me-too or follow-on drugs. There have been many comments for and against the dissemination of these incremental innovations but few papers have broached the subject from an econometric point of view, possibly because identification of me-too or follow-on drugs is not so obvious. This paper focuses on the impact of entry order on follow-on drug competition in the French market between the years 2001 and 2007. More precisely, this study examines the effects on market share of first entrants in the follow-on drug market and how this possible competitive advantage changes over time. First results are coherent with theoretical microeconomic issues concerning the importance of being first. We find evidence that first movers in the follow-on drug market have the ability to capture and maintain greater market share for a long period of time. The hierarchical market position of follow-on drugs does not seem to be affected by generic drug emergence. From a dynamic perspective, our analysis shows that market share is positively correlated with the ability of follow-on drugs to set prices higher than the average follow-on drug prices in a specific therapeutic class, which means that market power remains considerably important for first movers. Moreover, we found that the optimum level of innovation to maximize market share is the highest one. PMID:25501258

  3. Competition effects in the dynamics of tumor cords

    Science.gov (United States)

    Scalerandi, M.; Sansone, B. Capogrosso; Benati, C.; Condat, C. A.

    2002-05-01

    A general feature of cancer growth is the cellular competition for available nutrients. This is also the case for tumor cords, neoplasms forming cylindrical structures around blood vessels. Experimental data show that, in their avascular phase, cords grow up to a limit radius of about 100 μm, reaching a quasi-steady-state characterized by a necrotized area separating the tumor from the surrounding healthy tissue. Here we use a set of rules to formulate a model that describes how the dynamics of cord growth is controlled by the competition of tumor cells among themselves and with healthy cells for the acquisition of essential nutrients. The model takes into account the mechanical effects resulting from the interaction between the multiplying cancer cells and the surrounding tissue. We explore the influence of the relevant parameters on the tumor growth and on its final state. The model is also applied to investigate cord deformation in a region containing multiple nutrient sources and to predict the further complex growth of the tumor.

  4. A Modeling Approach to Simulate Effects of Intercropping and Interspecific Competition in Arable Crops

    OpenAIRE

    Heike Knörzer; Simone Graeff-Hönninger; Bettina U. Müller; Hans-Peter Piepho; Wilhelm Claupein

    2010-01-01

    Interspecific competition between species influences their individual growth and performance. Neighborhood effects become especially important in intercropping systems, and modeling approaches could be a useful tool to simulate plant growth under different environmental conditions to help identify appropriate combinations of different crops while managing competition. This study gives an overview of different competition models and their underlying modeling approaches. To model intercropping ...

  5. Belowground consequences of vegetation change and their treatment in models

    OpenAIRE

    Jackson, R.B.; Schenk, H J; Jobbagy, E G; Canadell, J.; Colello, G D; Dickinson, R E; Dunne, T.; Field, C.B.; Friedlingstein, P.; Heimann, M.; Hibbard, K.; Kicklighter, D W; A. Kleidon; R. P. Neilson; Parton, W.J.

    2000-01-01

    The extent and consequences of global land-cover and land-use change are increasingly apparent. One consequence not so apparent is the altered structure of plants belowground. This paper examines such belowground changes, emphasizing the interaction of altered root distributions with other factors and their treatment in models. Shifts of woody and herbaceous vegetation with deforestation, afforestation, and woody plant encroachment typically alter the depth and distribution of plant rests, in...

  6. Crop rotational diversity enhances belowground communities and functions in an agroecosystem.

    Science.gov (United States)

    Tiemann, L K; Grandy, A S; Atkinson, E E; Marin-Spiotta, E; McDaniel, M D

    2015-08-01

    Biodiversity loss, an important consequence of agricultural intensification, can lead to reductions in agroecosystem functions and services. Increasing crop diversity through rotation may alleviate these negative consequences by restoring positive aboveground-belowground interactions. Positive impacts of aboveground biodiversity on belowground communities and processes have primarily been observed in natural systems. Here, we test for the effects of increased diversity in an agroecosystem, where plant diversity is increased over time through crop rotation. As crop diversity increased from one to five species, distinct soil microbial communities were related to increases in soil aggregation, organic carbon, total nitrogen, microbial activity and decreases in the carbon-to-nitrogen acquiring enzyme activity ratio. This study indicates positive biodiversity-function relationships in agroecosystems, driven by interactions between rotational and microbial diversity. By increasing the quantity, quality and chemical diversity of residues, high diversity rotations can sustain soil biological communities, with positive effects on soil organic matter and soil fertility.

  7. Signal signature of aboveground-induced resistance upon belowground herbivory in maize

    OpenAIRE

    Erb, Matthias; Flors, Victor; Karlen, Danielle; De Lange, Elvira S.; Planchamp, Chantal; D’Alessandro, Marco; Turlings, Ted C. J.; Ton, Jurriaan

    2012-01-01

    Plants activate local and systemic defence mechanisms upon exposure to stress. This innate immune response is partially regulated by plant hormones, and involves the accumulation of defensive metabolites. Although local defence reactions to herbivores are well studied, less is known about the impact of root herbivory on shoot defence. Here, we examined the effects of belowground infestation by the western corn rootworm Diabrotica virgifera virgifera on aboveground resistance in maize. Belowgr...

  8. The effective strategic leadership in the global competitive environment

    OpenAIRE

    Miceski, Trajko

    2012-01-01

    This paper focuses on strategic leadership and its importance as a potential source of competitive advantage in today's era of globalization. Strategic leadership can be defined as ability to: influence without coercion, prediction, vision, maintaining flexibility, anticipation of positive change, mobilizing and effectuation of human resources and many other activities that allow the company to the forefront in the global competitive environment.

  9. Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success: a hypothesis.

    Science.gov (United States)

    Dawson, Wayne

    2015-10-01

    Our understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource-acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource uptake and competitive ability compared to native species in the alien range, and compared to plants of the invader in its native range. Such root-trait changes could be ecological or evolutionary in nature. I explain how shifts in root traits could occur as a consequence of enemy release and contribute to invasion success of alien plants, and how they could be interrelated with other potential belowground drivers of invasion success (allelopathy, mutualist enhancement). Finally, I outline the approaches that could be taken to test whether belowground enemy release results in increased competitive ability and nutrient uptake by invasive alien plants, via changes in root traits in the alien range.

  10. The co-evolution of brand effect and competitiveness in evolving networks

    CERN Document Server

    Guo, Jin-Li

    2013-01-01

    The principle that "the brand effect is attractive" underlies preferential attachment. If new connections are made preferentially to more popular nodes, then the degree distribution of nodes follows power laws. Here we show that the brand effect is just one element of attractiveness; another element is the competitiveness. We develop a framework that allows us to investigate this competitive aspect of real networks, instead of simply preferring popular nodes. As opposed to preferential attachment, our model accurately describes the evolution of social and technological networks. We find that this competition for links allows more competitive nodes to obtain the more connected but less competitive ones. The phenomenon which more competitive nodes get richer links can help us understand the evolution of many competitive systems in nature and society. Through theoretical analysis and numerical simulations, we also find that our model has not only the universality for the homogeneous weighted network, but also th...

  11. 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. PMID:24979812

  12. The Effectiveness of Trade Shows in Global Competition

    Directory of Open Access Journals (Sweden)

    JONIDA KELLEZI

    2013-06-01

    Full Text Available Trade shows industry has experienced a rapid growth during the last years. They are considered as a vital communication technique especially for those companies that operate in international markets and that aim to reach specific audiences. Making them an integral part of the marketing communication strategy enables companies in: developing customer relationships; offering possibilities for sales and sales promotion; undertaking and maintaining good international business relations; monitoring international competition as well as minimizing entry barriers in new markets. During the last years, many Albanian companies that operate in foreign businesses have started to engage in trade shows. Face to face meetings with their potential customers and direct competitors are among the most important reasons for investing in this marketing tool. Even though the literature regarding trade shows effectiveness is increasing constantly, research on its effectiveness is still limited. Therefore, the aim of this paper is to study the effectiveness of trade shows as a marketing communication tool. More specifically, it is focused in studying the usage of trade shows by Albanian companies when competing on international markets.

  13. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    CERN Document Server

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K

    2016-01-01

    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  14. 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......-shaped relationship between farm size and the costs imposed by manure management regulations. This results from the additional application and transport costs for large-scale producers, and the lack of scale advantages for smaller farms in meeting regulations. Costs imposed on producers by manure management...... regulations in different countries do not appear to be of a scale that could explain the general difference in pigmeat competitiveness between countries....

  15. The Effect of Advanced Management Accounting Practices on the Competitive Strategies and Performance

    OpenAIRE

    Rahmi Yücel; Kayhan Ahmetoğulları

    2015-01-01

    This study is based on a sample of 300 managers from the production industry of West Marmara Region. The goal of this study is to examine the interaction among advanced management accounting practices, competitive strategies and company performance. As a result of study, it is found that advanced accounting management practices have a positive effect on the company performance and competitive strategies. In addition, competitive strategies have an effect on the company performance positively....

  16. Assessing the Effectiveness of Competition Law Enforcement Policy in Relation to Cartels

    OpenAIRE

    Priit Mändmaa

    2014-01-01

    Despite the high fines for cartel infringements it is claimed that the current competition law enforcement lacks deterrent effect for the avoidance of cartel infringements and is procedurally fragile. This article analyses the current competition law enforcement policy in relation to cartels. More specifically, the article assesses the effectiveness of the policy in deterring the formation of cartels and pursuing the goals of competition law by analysing the theory of deterrence, case law, pr...

  17. The Economic Effect of Competition in the Air Transportation Industry

    Science.gov (United States)

    Hubbard, H. B.

    1972-01-01

    The air transportation industry has been described as a highly-competitive, regulated oligopoly or as a price-regulated cartel with blocked entry, resulting in excessive service and low load factors. The current structure of the industry has been strongly influenced by the hypotheses that increased levels of competition are desirable per se, and that more competing carriers can be economically supported in larger markets, in longer haul markets, with lower unit costs, and with higher fare levels. An elementary application of competition/game theory casts doubt on the validity of these hypotheses, but rather emphasizes the critical importance of the short-term non-variable costs in determining economic levels of competition.

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

    OpenAIRE

    Samira Ghazavi; Mahmood Reza Cheraghali

    2013-01-01

    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...

  19. The Effect of Regulated Competition on Pharmaceutical Advertising and Promotion

    OpenAIRE

    Guy David; Sara Markowitz

    2015-01-01

    Pharmaceutical advertising and promotion are distinct in that the firm’s decisions are highly interconnected with issues surrounding consumer safety. Expenditure decisions must balance profitable demand expansions with potential regulatory actions, and depend on the nature of competition (monopoly versus oligopoly). We develop a model of the firm’s choice of expenditures under different competitive scenarios with consideration of possible regulatory action. We test the model’s predictions wit...

  20. 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.

  1. Responses of belowground carbon allocation dynamics to extended shading in mountain grassland

    Science.gov (United States)

    Bahn, Michael; Lattanzi, Fernando A.; Hasibeder, Roland; Wild, Birgit; Koranda, Marianne; Danese, Valentina; Brüggemann, Nicolas; Schmitt, Michael; Siegwolf, Rolf; Richter, Andreas

    2014-05-01

    Carbon (C) allocation strongly influences plant and soil processes. Short-term C allocation dynamics in ecosystems and their responses to environmental changes are still poorly understood. Using in situ 13CO2 pulse labeling, we studied the effects of one week of shading on the transfer of recent photoassimilates between sugars and starch of above- and belowground plant organs and to soil microbial communities of a mountain meadow. C allocation to roots and microbial communities was rapid. Shading strongly reduced sucrose and starch concentrations in shoots, but not roots, and affected tracer dynamics in sucrose and starch of shoots, but not roots: recent C was slowly incorporated into root starch irrespective of the shading treatment. Shading reduced leaf respiration more strongly than root respiration. It caused no reduction in the amount of 13C incorporated into fungi and gram-negative bacteria, but increased its residence time. These findings suggest that, under interrupted C supply, belowground C allocation (as reflected by the amount of tracer allocated to root starch, soil microbial communities and belowground respiration) was maintained at the expense of aboveground C status, and that C source strength may affect the turnover of recent plant-derived C in soil microbial communities. (Reference: Bahn et al. 2013. New Phytologist 198:116-126)

  2. Belowground rhizomes in paleosols: The hidden half of an Early Devonian vascular plant.

    Science.gov (United States)

    Xue, Jinzhuang; Deng, Zhenzhen; Huang, Pu; Huang, Kangjun; Benton, Michael J; Cui, Ying; Wang, Deming; Liu, Jianbo; Shen, Bing; Basinger, James F; Hao, Shougang

    2016-08-23

    The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant-soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet-dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant-soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated. PMID:27503883

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

    NARCIS (Netherlands)

    Blomqvist, M.M.; Olff, H.; Blaauw, M.B.; Bongers, T.; Van der Putten, 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 abovegro

  4. 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.

  5. 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....

  6. 75 FR 24969 - China's Agricultural Trade: Competitive Conditions and Effects on U.S. Exports

    Science.gov (United States)

    2010-05-06

    ... COMMISSION China's Agricultural Trade: Competitive Conditions and Effects on U.S. Exports AGENCY: United.... International Trade Commission (Commission) instituted investigation No. 332-518, China's Agricultural Trade... on the conditions of competition in China's agricultural market and trade and their effect on...

  7. Behaviourally mediated indirect effects : interference competition increases predation mortality in foraging redshanks

    NARCIS (Netherlands)

    Minderman, J; Lind, J; Cresswell, W

    2006-01-01

    The effect of competition for a limiting resource on the population dynamics of competitors is usually assumed to operate directly through starvation, yet may also affect survival indirectly through behaviourally mediated effects that affect risk of predation. Thus, competition can affect more than

  8. 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.

  9. 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...

  10. 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.

  11. Spatial heterogeneity of plant-soil feedback affects root interactions and interspecific competition.

    Science.gov (United States)

    Hendriks, Marloes; Ravenek, Janneke M; Smit-Tiekstra, Annemiek E; van der Paauw, Jan Willem; de Caluwe, Hannie; van der Putten, Wim H; de Kroon, Hans; Mommer, Liesje

    2015-08-01

    Plant-soil feedback is receiving increasing interest as a factor influencing plant competition and species coexistence in grasslands. However, we do not know how spatial distribution of plant-soil feedback affects plant below-ground interactions. We investigated the way in which spatial heterogeneity of soil biota affects competitive interactions in grassland plant species. We performed a pairwise competition experiment combined with heterogeneous distribution of soil biota using four grassland plant species and their soil biota. Patches were applied as quadrants of 'own' and 'foreign' soils from all plant species in all pairwise combinations. To evaluate interspecific root responses, species-specific root biomass was quantified using real-time PCR. All plant species suffered negative soil feedback, but strength was species-specific, reflected by a decrease in root growth in own compared with foreign soil. Reduction in root growth in own patches by the superior plant competitor provided opportunities for inferior competitors to increase root biomass in these patches. These patterns did not cascade into above-ground effects during our experiment. We show that root distributions can be determined by spatial heterogeneity of soil biota, affecting plant below-ground competitive interactions. Thus, spatial heterogeneity of soil biota may contribute to plant species coexistence in species-rich grasslands.

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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.

  14. 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

  15. 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

  16. Analysis of Individual Tree Competition Effect on Diameter Growth of Silver Birch in Estonia

    Directory of Open Access Journals (Sweden)

    Kobra Maleki

    2015-08-01

    Full Text Available Aim of study: The present study evaluates a set of competition indices including spatially explicit indices combined with different competitor selection approaches and non-spatially explicit competition indices. The aim was to quantify and describe the neighbouring effects on the tree diameter growth of silver birch trees. Area of study: Region throughout Estonia. Material and methods: Data from the Estonian Network of Forest Research Plots was used. After quantifying the selected indices, the best non-spatial indices and spatial indices (combined with neighbour selection methods were separately devised into a growth model as a predictor variable to assess the ability of the diameter growth model before and after adding competition measures. To test the species-specific effect on the competition level, the superior indices were recalculated using Ellenberg’s light indicators and incorporated into the diameter growth model. Main results: Statistical analyses showed that the diameter growth is a function of neighbourhood interactions and spatial indices were better growth predictors than non-spatial indices. In addition, the best selections of competitive neighbours were acquired based on the influence zone and the competition elimination angle concepts, and using Ellenberg’s light values had no significant improvement in quantifying the competition effects. Research highlights: Although the best ranking spatial competition measures were superior to the best non-spatial indices, the differences were negligible.

  17. 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.

  18. Competitive energy markets. The effective route to improving the environment

    International Nuclear Information System (INIS)

    The objective of this paper is to demonstrate how market forces, operating in an increasingly competitive energy market, are a preferred route to achieving environmental and energy efficiency benefits than those which can be achieved through a managed approach adopted by many governments. It shows, through UK examples such as shifting to electricity in several industrial processes, how electricity is a catalyst for change at several levels in business, the community and the general economy

  19. Effects of Noise in Symmetric Two-Species Competition

    Science.gov (United States)

    Vilar, José M. G.; Solé, Ricard V.

    1998-05-01

    We have analyzed the interplay between noise and periodic modulations in a classical Lotka-Volterra model of two-species competition. We have found that the consideration of noise changes drastically the behavior of the system and leads to new situations which have no counterpart in the deterministic case. Among others, noise is responsible for temporal oscillations, spatial patterns, and the enhancement of the response of the system via stochastic resonance.

  20. Electronic Health Information Exchange, Competition, and Network Effects

    OpenAIRE

    Sunita Desai

    2014-01-01

    As in most industries, in health care, information is a competitive asset, and we expect that health care providers may have incentive to protect their information from competitors. This study aims to understand how this incentive to protect information may be a barrier to the development of a health information network. Health information networks are designed to facilitate electronic information sharing across health care providers. The electronic exchange of health information is widely co...

  1. Does school competition matter? : Effects of a large-scale school choice reform on student performance

    OpenAIRE

    Ahlin, Åsa

    2003-01-01

    The effect of a general school choice reform on student performance is studied in a Swedish institutional setting. A rich set of individual level data allows estimation of a value added specification, mitigating problems with omission of relevant variables. Increased school competition is shown to have statistically significant positive effects on student performance in mathematics, but no significant effects in English and Swedish. Interacting school competition with student characteristics,...

  2. Electrophysiological evidence for emotional valence and competitive arousal effects on insight problem solving.

    Science.gov (United States)

    Li, Yadan; Xiao, Xiao; Ma, Wenjuan; Jiang, Jun; Qiu, Jiang; Zhang, Qinglin

    2013-11-13

    Accumulating evidence suggests that insight can be substantially influenced by task-irrelevant emotion stimuli and interpersonal competitive situation, and a close link might exist between them. Using a learning-testing paradigm and Event-Related Potentials (ERPs), the present study investigated the independent and joint effects of emotional and competitive information on insight problem solving especially their neural mechanisms. Subjects situated in either competitive or non-competitive condition learned heuristic logogriphs first and then viewed task-irrelevant positive or negative emotional pictures, which were followed by test logogriphs to solve. Both behavioral and ERP findings showed a more evident insight boost following negative emotional pictures in competitive context. Results demonstrated that negative emotion and competitive situation might promote insight by a defocused mode of attention (as indicated by N1 and P2), the enhanced semantic integration and breaking mental set (as indicated by N450), and the increased forming of novel associations activated by motivational arousal originating from competition (as indicated by P800-1600 and P1600-2500). These results indicate that the dynamic interactions between emotional valence and competitive arousal effects on insight.

  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. PMID:26024811

  5. Issues and prospects of belowground ecology with special reference to global climate change

    Institute of Scientific and Technical Information of China (English)

    HE Jinsheng; WANG Zhengquan; FANG Jingyun

    2004-01-01

    The theory of ecology is based on over 100 a of research and investigation, all centered on aboveground patterns and processes. However, as contemporary ecologists are increasingly acknowledging, belowground structures, functions, and processes are some of the most poorly understood areas in ecology. This lack of understanding of belowground ecological processes seriously restricts the advance of global change research. The interdisciplinary field of belowground ecology began to flourish in the 1990s, along with the expansion of global change research, and quickly gained momentum. Belowground ecology aims to investigate belowground structures, functions, and processes, as well as their relationships with corresponding aboveground features, emphasizing the responses of belowground systems under global change conditions. Key research areas include root ecology,belowground animals, and soil microorganisms. This review summarizes and analyzes the relationships between aboveand belowground ecosystems, root ecology, root biogeography, belowground biodiversity, as well as research areas with particular challenges and progress. This commentary emphasizes certain theoretical issues concerning the responses of belowground processes to global change, and concludes that belowground ecology is a critical research priority in the 21st century.

  6. The Effect of Advanced Management Accounting Practices on the Competitive Strategies and Performance

    Directory of Open Access Journals (Sweden)

    Rahmi Yücel

    2015-10-01

    Full Text Available This study is based on a sample of 300 managers from the production industry of West Marmara Region. The goal of this study is to examine the interaction among advanced management accounting practices, competitive strategies and company performance. As a result of study, it is found that advanced accounting management practices have a positive effect on the company performance and competitive strategies. In addition, competitive strategies have an effect on the company performance positively. Furthermore, there is a positive and significant relation between long-term strategy based on management accounting practices and non-financial company performance and between activity based on management accounting practices and financial performance.

  7. Effect of male age on sperm traits and sperm competition success in the guppy (Poecilia reticulata).

    Science.gov (United States)

    Gasparini, C; Marino, I A M; Boschetto, C; Pilastro, A

    2010-01-01

    Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the offspring. We tested this hypothesis in the guppy (Poecilia reticulata), a species characterized by polyandry and intense sperm competition, by investigating whether age affects post-copulatory male traits and sperm competition success. Females did not discriminate between old and young males in a mate choice experiment. While old males produced longer and slower sperm with larger reserves of strippable sperm, compared to young males, artificial insemination did not reveal any effect of age on sperm competition success. Altogether, these results do not support the hypothesis that polyandry evolved in response to costs associated with mating with old males in the guppy.

  8. 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.

  9. Exchange rate volatility effects on export competitiveness. Romanian Case

    Directory of Open Access Journals (Sweden)

    Anca GHERMAN

    2013-09-01

    Full Text Available In this paper we determine and analyze the impact of the exchange rate variation over the international trade of Romania. We highlighted the sense of the relationship between exchange rate and exports or imports, but the intensity between the variables and the lags that characterize the interdependency between them. In the context of actual great imbalances in the global economy and other risks (financial, political or social that drive to the decrease in aggregate demand on global level, we consider that external competitivity became one of the key variable for the economic growth in Romania like an integrated process in the European economy.

  10. Competitive effects of Basel II on U.S. bank credit card lending

    OpenAIRE

    William W. Lang; Loretta J. Mester; Todd A. Vermilyea

    2007-01-01

    The authors analyze the potential competitive effects of the proposed Basel II capital regulations on U.S. bank credit card lending. They find that bank issuers operating under Basel II will face higher regulatory capital minimums than Basel I banks, with differences due to the way the two regulations treat reserves and gain-on-sale of securitized assets. During periods of normal economic conditions, this is not likely to have a competitive effect; however, during periods of substantial stres...

  11. Interactive Effect of Herbivory and Competition on the Invasive Plant Mikania micrantha

    OpenAIRE

    Junmin Li; Tao Xiao; Qiong Zhang; Ming Dong

    2013-01-01

    A considerable number of host-specific biological control agents fail to control invasive plants in the field, and exploring the mechanism underlying this phenomenon is important and helpful for the management of invasive plants. Herbivory and competition are two of the most common biotic stressors encountered by invasive plants in their recipient communities. We predicted that the antagonistic interactive effect between herbivory and competition would weaken the effect of herbivory on invasi...

  12. Belowground carbon trade among tall forest trees

    Science.gov (United States)

    Klein, Tamir; Siegwolf, Rolf; Koerner, Christian

    2016-04-01

    Just imagine one tree could hand over large quantities of carbon to another tree. How would that change our thinking about carbon relations of forests, the single biggest biological C reservoir on earth? If such a tree-to-tree C shuttle would exist, it required a demand-supply gradient and a pipeline. Here we show that exactly this unthinkable does occur in overlapping root spheres of tall trees in a mixed temperate forest. Using canopy scale stable carbon isotope labelling applied from a construction crane, we demonstrate that carbon assimilated by spruce is traded over to neighbouring beech, larch, and pine in amounts so large that fine roots almost equilibrate the carbon source signature. The isotope mixing ratio indicated that the interspecific transfer accounted for 40% of the fine root carbon, which is ca. 280 kg ha-1 a-1. This is the first forest scale evidence of a large flux of carbon among mature trees from evolutionary distant taxa. Carbon transfer most likely occurred through common ectomycorrhiza networks, which also exhibited the labelled carbon signal. These observations indicate that while competition for resources (e.g. light, water, nutrients) is often considered the dominant tree-tree interaction in a forest, trees actually interact in more complex pathways including a massive carbon exchange.

  13. 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.

  14. 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. PMID:20002162

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

    International Nuclear Information System (INIS)

    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

  16. Blue judogi may bias competitive performance when seeding system is not used: sex, age, and level of competition effects.

    Science.gov (United States)

    Julio, Ursula F; Miarka, Bianca; Rosa, João P P; Lima, Giscard H O; Takito, Monica Y; Franchini, Emerson

    2015-02-01

    This study evaluated whether the judogi colour (blue or white) could influence a combat outcome (victory or defeat) in 1,233 judo official combats. Sex, age group, and level of competition were also considered in the analysis. Binomial probability tests showed a higher probability of an athlete's winning a combat wearing blue judogi for both sexes, levels of competition (regional and state), and for the athletes of the junior and senior categories. Thus, blue judogi may bias competitive outcome for both sexes in regional and state level competitions and for athletes above junior age. PMID:25650512

  17. The Effects of Environmental Factors on the Growth and Competition of Algae

    Institute of Scientific and Technical Information of China (English)

    Jing; WANG; Jiazhang; CHEN; Shunlong; MENG

    2013-01-01

    In order to study the effect of environmental factors on the algae growth and competition,the author summarized overseas and domestic related researches in recent years.Most of the researches are about the influence of single factor on growth of algae.However,there is insufficient investment on the interaction of different factors and the competition between algae growth.This paper briefly introduced the classification of algae and the role they played in ecological system and focused on the influence which included temperature,illumination,nitrogen,phosphorus and pH on the growth and competition of algal.In the end,the author proposed key questions which were still needed to be studied in order to know more about the relationship between environment effects and growth and competition of algae.Therefore,people could better improve the community structure of algae and water ecological environment,and improve water primary productivity.

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

    OpenAIRE

    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; André A Dhondt

    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 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 ...

  19. Effects of client symbiosis to the competitiveness of the commercial business hotel

    OpenAIRE

    Wang, Yali; Gao, Hong

    2008-01-01

    There are many researches on the satisfaction of the clients and the competitiveness of the enterprise in present days, but this dissertation focuses on the aspect of the client symbiosis, an factor to influence the competitiveness of one enterprise, intending to research on the foundation and maintenance of the symbiosis between the enterprise and client besides its effects to the satisfaction of the clients. The relationship has transfer from what you do to and for your clients to what you ...

  20. Effect of dispersal and nutrient availability on the competitive ability of toxin-producing yeast

    OpenAIRE

    Wloch-Salamon, Dominika M; Gerla, Daan; Hoekstra, Rolf F.; de Visser, J. Arjan G.M.

    2008-01-01

    The ecological role of interference competition through toxin production is not well understood. In particular, it is unclear under what conditions the benefits of toxic killing outweigh the metabolic costs involved. A killer advantage has been suggested to rely on local competitive interactions where the benefits of killing accrue to the toxin producer preferentially, but this notion has little empirical support. In addition, contrasting predictions exist about the effect of resource abundan...

  1. How Does School Choice Improve Student Achievement? Estimating School-level Competitive Effects and Student-level Peer Effects

    OpenAIRE

    Jinnai, Yusuke; 陣内, 悠介

    2016-01-01

    Although school choice programs have played a key role in public education reform in the United States for years, the impact of competition between schools on student achievement remains unclear. This study examines the effects of introducing charter schools on students at neighboring traditional public schools. Unlike prior work, which estimates the effects of charter schools as a whole, I present that such impact consists of school-level competitive eff ects and student-level peer effects. ...

  2. 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.

  3. Carbon budget for Scots pine trees: effects of size, competition and site fertility on growth allocation and production.

    Science.gov (United States)

    Vanninen, Petteri; Mäkelä, Annikki

    2005-01-01

    Time series of carbon fluxes in individual Scots pine (Pinus sylvestris L.) trees were constructed based on biomass measurements and information about component-specific turnover and respiration rates. Foliage, branch, stem sapwood, heartwood and bark components of aboveground biomass were measured in 117 trees sampled from 17 stands varying in age, density and site fertility. A subsample of 32 trees was measured for belowground biomass excluding fine roots. Biomass of fine roots was estimated from the results of an earlier study. Statistical models were constructed to predict dry mass (DW) of components from tree height and basal area, and time derivatives of these models were used to estimate biomass increments from height growth and basal area growth. Biomass growth (G) was estimated by adding estimated biomass turnover rates to increments, and gross photosynthetic production (P) was estimated by adding estimated component respiration rates to growth. The method, which predicts the time course of G, P and biomass increment in individual trees as functions of height growth and basal area growth, was applied to eight example trees representing different dominance positions and site fertilities. Estimated G and P of the example trees varied with competition, site fertility and tree height, reaching maximum values of 22 and 43 kg(DW) year(-1), respectively. The site types did not show marked differences in productivity of trees of the same height, although height growth was greater on the fertile site. The G:P ratio decreased with tree height from 65 to 45%. Growth allocation to needles and branches increased with increasing dominance, whereas growth allocation to the stem decreased. Growth allocation to branches decreased and growth allocation to coarse roots increased with increasing tree size. Trees at the poor site allocated 49% more to fine roots than trees at the fertile site. The belowground parts accounted for 25 to 55% of annual G, increasing with tree size

  4. 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. PMID:22489544

  5. 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.

  6. 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.

  7. The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton.

    Science.gov (United States)

    Zhou, Wenqing; Starr, James L; Krumm, Janice L; Sword, Gregory A

    2016-10-01

    Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop. PMID:27451418

  8. 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.

    2016-01-01

    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

  9. Impacts of farming practice within organic farming systems on below-ground ecology and ecosystem function

    OpenAIRE

    Stockdale, E A; Phillips, L; Watson, C. A.

    2006-01-01

    Maintaining ecosystem function is a key issue for sustainable farming systems which contribute broadly to global ecosystem health. A focus simply on the diversity of belowground organisms is not sufficient and there is a need to consider the contribution of below-ground biological processes to the maintenance and enhancement of soil function and ecosystem services. A critical literature review on the impacts of land management practices on below-ground ecology and function shows that farm man...

  10. Effect of 10 Week Beta-Alanine Supplementation on Competition and Training Performance in Elite Swimmers

    Directory of Open Access Journals (Sweden)

    Louise M. Burke

    2012-10-01

    Full Text Available Although some laboratory-based studies show an ergogenic effect with beta-alanine supplementation, there is a lack of field-based research in training and competition settings. Elite/Sub-elite swimmers (n = 23 males and 18 females, age = 21.7 ± 2.8 years; mean ± SD were supplemented with either beta-alanine (4 weeks loading phase of 4.8 g/day and 3.2 g/day thereafter or placebo for 10 weeks. Competition performance times were log-transformed, then evaluated before (National Championships and after (international or national selection meet supplementation. Swimmers also completed three standardized training sets at baseline, 4 and 10 weeks of supplementation. Capillary blood was analyzed for pH, bicarbonate and lactate concentration in both competition and training. There was an unclear effect (0.4%; ±0.8%, mean, ±90% confidence limits of beta-alanine on competition performance compared to placebo with no meaningful changes in blood chemistry. While there was a transient improvement on training performance after 4 weeks with beta-alanine (−1.3%; ±1.0%, there was an unclear effect at ten weeks (−0.2%; ±1.5% and no meaningful changes in blood chemistry. Beta-alanine supplementation appears to have minimal effect on swimming performance in non-laboratory controlled real-world training and competition settings.

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

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Andreas [Department of Economics, University of Oldenburg, 26111 Oldenburg (Germany)

    2010-09-15

    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)

  12. Females make tough neighbors: sex-specific competitive effects in seedlings of a dioecious grass.

    Science.gov (United States)

    Eppley, Sarah M

    2006-01-01

    If males and females of a species differ in their effect on intraspecific competition then this can have significant ecological and evolutionary consequences because it can lead to size and mortality disparities between the sexes, and thus cause biased population sex ratios. If the degree of sexual dimorphism of competitive effect varies across environments then this variation can generate sex ratio variation within and between populations. In a California population of Distichlis spicata, a dioecious grass species exhibiting extreme within-population sex ratio variation (spatial segregation of the sexes), I evaluated the intraspecific competitive effects of male and female D. spicata seedlings in three soil types. The sex of seedlings was determined using a RAPD-PCR marker co-segregating with female phenotype. Distichlis spicata seedlings, regardless of sex, were six times larger when grown with male versus female conspecific seedlings in soil from microsites where the majority of D. spicata plants are female, and this sexual dimorphism of competitive effect was weaker or did not occur in other soil types. This study suggests that it is not just the higher costs of female versus male reproduction itself that cause spatial segregation of the sexes in D. spicata, but that differences in competitive abilities between the sexes--which occur as early as the seedling stage--can generate sex ratio variation.

  13. Reforms in the French power system: from weak contestability to effective competition?

    Energy Technology Data Exchange (ETDEWEB)

    Finon, Dominique [Centre National de la Recherche Scientifique, Inst. d' Economie et de Politique de l' Energie, Grenoble, 38 (France); Grenoble Univ., Grenoble, 38 (France)

    2001-08-01

    One way to introduce competition in the power industries is to preserve the integration of the incumbent companies and to organise the access of potential competitors to the network on a fair basis. But the combination of hierarchy and bilateral contracts between entrants (IPP candidates, foreign producers, intermediaries), suppliers and consumers appears to be unstable because of permanent tensions between the incumbent's dominant position and fair competition. Moreover, in an institutional environment enlarged by the supranational powers of the European Union, heterogeneity of rules and structures between quasi-integrated power industries and decentralised competitive ones are sources of permanent questioning. The paper analyses the stability of the recent reform of the French power industry, the extreme integration of which being deeply rooted in the French institutional peculiarities, has been weakly affected by the Directive 96/92 transcription. Two institutional scenarios are defined, which give a different weight to two competition paradigms in conflicts: one pertains to the industrial policy (which inclines to preserve hierarchy in the national area to gain national champion's competitive advantages in the European as in the global field), and the other to the neo-classical paradigm of effective competition. In the first scenario, the integration of the industrial organisation is preserved but with transparent grid access rules supposed to create an actual market contestability, and the playing field is the continental Europe on which national champions compete. In the second one, the French industrial organisation has to conform to the competitive model, with vertical and horizontal disintegration and creation of a power exchange market for promoting competition. But this scenario is heavily strained by the institutional determinism of the nuclear legacy. The future reality should be set between these two scenarios. (Author)

  14. Above- and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

  15. Above- and belowground biomass in relation to environmental factors in temperate grasslands, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    MA WenHong; YANG YuanHe; HE JinSheng; ZENG Hui; FANG JingYun

    2008-01-01

    Above- and belowground biomasses of grasslands are important parameters for characterizing regional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed information for aboveground biomass (AGB), belowground biomass (BGB) Is poorly reported at the regional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots,and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

  16. 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…

  17. The interaction between dispersal, the Allee effect and scramble competition affects population dynamics

    NARCIS (Netherlands)

    Etienne, R.; Wertheim, B.; Hemerik, L.; Schneider, P.; Powell, J.

    2002-01-01

    Many organisms experience an Allee effect: their populations do not grow optimally at low densities. In addition, individuals compete with one another at high densities. The Allee effect and competition thus create a lower and an upper bound to local population size. Local populations can, however,

  18. The interaction between dispersal, the Allee effect and scramble competition affects population dynamics

    NARCIS (Netherlands)

    Etienne, R; Wertheim, B; Hemerik, L; Schneider, P; Powell, J

    2002-01-01

    Many organisms experience an Allee effect: their populations do not grow optimally at low densities. In addition, individuals compete with one another at high densities. The Allee effect and competition thus create a lower and an upper bound to local population size. Local populations can, however.

  19. 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.

  20. 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. PMID:10338929

  1. Assessing the Effectiveness of Competition Law Enforcement Policy in Relation to Cartels

    Directory of Open Access Journals (Sweden)

    Priit Mändmaa

    2014-11-01

    Full Text Available Despite the high fines for cartel infringements it is claimed that the current competition law enforcement lacks deterrent effect for the avoidance of cartel infringements and is procedurally fragile. This article analyses the current competition law enforcement policy in relation to cartels. More specifically, the article assesses the effectiveness of the policy in deterring the formation of cartels and pursuing the goals of competition law by analysing the theory of deterrence, case law, procedural norms, imposed fines and academic literature. The main conclusions are that wrong targets are aimed at under the deterrence principle, the proceedings are of a criminal law nature and require a separation of powers, and that the current level of fines does not pose a threat on the economy and continually fail to deter price-fixing.

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

    International Nuclear Information System (INIS)

    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)

  3. Variation in the relative magnitude of intraspecific and interspecific competitive effects in novel versus familiar environments in two Drosophila species

    Indian Academy of Sciences (India)

    Amitabh Joshi

    2004-08-01

    Models of competitor coevolution, especially the genetic feedback hypothesis, suggest that a negative correlation between intraspecific and interspecific competitive effects may be important in sustaining competitor coexistence, and can give rise to oscillatory dynamics with repeated reversals of competitive superiority. I reanalyzed previously published census data from an experiment in which populations of Drosophila melanogaster and D. simulans underwent competitive coevolution in one familiar and two novel environments, to specifically look for any evidence of a negative relationship between intraspecific and interspecific competitive effects on population growth rates, and for any indication of short period cycling in the relative magnitude of intraspecific and interspecific competitive effects. While there was considerable variation in the relative magnitude of intraspecific and interspecific competitive effects over generations, among both populations and environments, there was no clear evidence supporting the genetic feedback hypothesis. Intraspecific and interspecific competitive effects on population growth rates were strongly positively correlated in novel environments, and uncorrelated in the familiar environment. Data from the familiar environment indicated that indices of competition of populations of the initially superior competitor, D. melanogaster, might be showing some cyclic behaviour, but I argue that this is likely to be transient, and not suggestive of sustained oscillatory dynamics predicted by the genetic feedback model. I discuss the results in the context of the importance of the genetic architecture of intraspecific and interspecific competitive abilities in determining the coevolutionary trajectory of competitive interactions.

  4. Advertising Effectiveness, Digital Video Recorders, and Product Market Competition

    OpenAIRE

    Bikram Ghosh; Axel Stock

    2010-01-01

    With increasing fragmentation of media markets and recent advances in technology, loss of advertising effectiveness has been a great concern for marketers. For consumers, the digital video recorder (DVR) offers the possibility to fast-forward through live programming. Whereas the DVR thus benefits consumers by reducing nuisance from commercials, industry observers believe that it may diminish advertisers' profits by rendering commercials ineffective. We use a model of informative advertising ...

  5. Understanding the joint effects of Cognitive Distance and Competition on Pioneering Innovations through the Dynamics between Suppliers and Competitors

    DEFF Research Database (Denmark)

    Li, Ying; Salomo, Søren

    2010-01-01

    for firms to take these potential opportunities. As far as innovation is concerned, the joint effects of cognitive distance and competition have only been roughly discussed and rarely investigated in an empirical setting in the literature. Thus, the aim of this study is not only to empirically test...... the individual effects of cognitive distance and competition on innovation but also try to understand their joint effects in a coherent way based on a resource-based view and through the product life cycle as a link of cognitive distance and competition. Competition is multidimensional and innovation has many...... between cognitive distance and pioneering innovations, and a negative effect of competition on pioneering innovations. It also suggests that the relationship between cognitive distance and pioneering innovations is negatively moderated by competition. These findings and the research design in this study...

  6. The Effect of Intra- and Interspecific Competition on Coexistence in Multispecies Communities.

    Science.gov (United States)

    Barabás, György; J Michalska-Smith, Matthew; Allesina, Stefano

    2016-07-01

    For two competing species, intraspecific competition must exceed interspecific competition for coexistence. To generalize this well-known criterion to multiple competing species, one must take into account both the distribution of interaction strengths and community structure. Here we derive a multispecies generalization of the two-species rule in the context of symmetric Lotka-Volterra competition and obtain explicit stability conditions for random competitive communities. We then explore the influence of community structure on coexistence. Results show that both the most and least stabilized cases have striking global structures, with a nested pattern emerging in both cases. The distribution of intraspecific coefficients leading to the most and least stabilized communities also follows a predictable pattern that can be justified analytically. In addition, we show that the size of the parameter space allowing for feasible communities always increases with the strength of intraspecific effects in a characteristic way that is independent of the interspecific interaction structure. We conclude by discussing possible extensions of our results to nonsymmetric competition. PMID:27322128

  7. Real Effective Exchange Rate of Rouble and Competitiveness of Russian Agrarian Producers

    Directory of Open Access Journals (Sweden)

    Mansoor Maitah

    2016-06-01

    Full Text Available A number of development projects were launched in Russia to support agro-producers, emphasizing increasing potential and perspective significance of Agrarian sector in the Russian economy. In light of this, it becomes interesting to investigate the position of agro-producers both in comparison to producers from other domestic sectors and relatively to its main foreign competitors. An analysis of the recent dynamics (from 2000 to 2014 of the real effective exchange rate of Russian rouble serves in the present study as an indicator of price competitiveness, which determines relative position of domestic producers in external markets. The actual competitive state of Russian agro-producers is analyzed by the means of revealed comparative advantage indices proposed by Balassa, Vollrath and Lafay. The calculations have shown that the entire analyzed period can be generally characterized as the period of significant real appreciation of the Russian rouble and the reason behind this is the difference in inflation rates in Russia and its main foreign trade partners. This predetermined the relatively low price competitiveness of agro-producers, which was mostly confirmed by calculated values of Balassa Revealed Comparative Advantage (RCA index, Vollrath Revealed Competitiveness index (VRC and Lafay Trade Specialization index (LFI. The short-term real depreciations of the rouble did not have any expected substantially positive impacts on their competitive position.

  8. The Effect of Intra- and Interspecific Competition on Coexistence in Multispecies Communities.

    Science.gov (United States)

    Barabás, György; J Michalska-Smith, Matthew; Allesina, Stefano

    2016-07-01

    For two competing species, intraspecific competition must exceed interspecific competition for coexistence. To generalize this well-known criterion to multiple competing species, one must take into account both the distribution of interaction strengths and community structure. Here we derive a multispecies generalization of the two-species rule in the context of symmetric Lotka-Volterra competition and obtain explicit stability conditions for random competitive communities. We then explore the influence of community structure on coexistence. Results show that both the most and least stabilized cases have striking global structures, with a nested pattern emerging in both cases. The distribution of intraspecific coefficients leading to the most and least stabilized communities also follows a predictable pattern that can be justified analytically. In addition, we show that the size of the parameter space allowing for feasible communities always increases with the strength of intraspecific effects in a characteristic way that is independent of the interspecific interaction structure. We conclude by discussing possible extensions of our results to nonsymmetric competition.

  9. On a competitive system under chemotactic effects with non-local terms

    International Nuclear Information System (INIS)

    In this paper, we study a system of partial differential equations describing the evolution of a population under chemotactic effects with non-local reaction terms. We consider an external application of chemoattractant in the system and study the cases of one and two populations in competition. By introducing global competitive/cooperative factors in terms of the total mass of the populations, we obtain, for a range of parameters, that any solution with positive and bounded initial data converges to a spatially homogeneous state with positive components. The proofs rely on the maximum principle for spatially homogeneous sub- and super-solutions. (paper)

  10. 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 chan

  11. 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 replace

  12. The Effects of Information Technology Applications on Collaborating Capability in Achieving Organisational Competitive Advantages in Malaysia

    OpenAIRE

    Lew Sook Ling; Ong Puay Tee; Uchenna Cyril Eze

    2013-01-01

    Emerging and developing countries, particularly in Asia, have seen relatively strong economic growth. Withright information technology (IT) adoption, the strong growth would provide a great advantage in improving thepotential of the growth of companies. This paper highlights information technology (IT) applications havemoderating effects towards collaborating capability-organisational competitive advantage relationship based onempirical justifications of 295 Multimedia Super Corridor (MSC) Ma...

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

    NARCIS (Netherlands)

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

    2005-01-01

    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. Fictional citizens and real effects: accountability to citizens in competitive and monopolistic markets

    NARCIS (Netherlands)

    Meijer, A.J.; Schillemans, T.

    2009-01-01

    This paper evaluates the influence of market conditions – (semi) competitive versus monopolistic markets –on (the effects of) citizen accountability on public sector organisations. Empirical material from case studies in education, healthcare, social security and land registry in the Netherlands is

  15. 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.

  16. 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

  17. Estimating the Effect of Competition on Trait Evolution Using Maximum Likelihood Inference.

    Science.gov (United States)

    Drury, Jonathan; Clavel, Julien; Manceau, Marc; Morlon, Hélène

    2016-07-01

    Many classical ecological and evolutionary theoretical frameworks posit that competition between species is an important selective force. For example, in adaptive radiations, resource competition between evolving lineages plays a role in driving phenotypic diversification and exploration of novel ecological space. Nevertheless, current models of trait evolution fit to phylogenies and comparative data sets are not designed to incorporate the effect of competition. The most advanced models in this direction are diversity-dependent models where evolutionary rates depend on lineage diversity. However, these models still treat changes in traits in one branch as independent of the value of traits on other branches, thus ignoring the effect of species similarity on trait evolution. Here, we consider a model where the evolutionary dynamics of traits involved in interspecific interactions are influenced by species similarity in trait values and where we can specify which lineages are in sympatry. We develop a maximum likelihood based approach to fit this model to combined phylogenetic and phenotypic data. Using simulations, we demonstrate that the approach accurately estimates the simulated parameter values across a broad range of parameter space. Additionally, we develop tools for specifying the biogeographic context in which trait evolution occurs. In order to compare models, we also apply these biogeographic methods to specify which lineages interact sympatrically for two diversity-dependent models. Finally, we fit these various models to morphological data from a classical adaptive radiation (Greater Antillean Anolis lizards). We show that models that account for competition and geography perform better than other models. The matching competition model is an important new tool for studying the influence of interspecific interactions, in particular competition, on phenotypic evolution. More generally, it constitutes a step toward a better integration of interspecific

  18. Estimating the Effect of Competition on Trait Evolution Using Maximum Likelihood Inference.

    Science.gov (United States)

    Drury, Jonathan; Clavel, Julien; Manceau, Marc; Morlon, Hélène

    2016-07-01

    Many classical ecological and evolutionary theoretical frameworks posit that competition between species is an important selective force. For example, in adaptive radiations, resource competition between evolving lineages plays a role in driving phenotypic diversification and exploration of novel ecological space. Nevertheless, current models of trait evolution fit to phylogenies and comparative data sets are not designed to incorporate the effect of competition. The most advanced models in this direction are diversity-dependent models where evolutionary rates depend on lineage diversity. However, these models still treat changes in traits in one branch as independent of the value of traits on other branches, thus ignoring the effect of species similarity on trait evolution. Here, we consider a model where the evolutionary dynamics of traits involved in interspecific interactions are influenced by species similarity in trait values and where we can specify which lineages are in sympatry. We develop a maximum likelihood based approach to fit this model to combined phylogenetic and phenotypic data. Using simulations, we demonstrate that the approach accurately estimates the simulated parameter values across a broad range of parameter space. Additionally, we develop tools for specifying the biogeographic context in which trait evolution occurs. In order to compare models, we also apply these biogeographic methods to specify which lineages interact sympatrically for two diversity-dependent models. Finally, we fit these various models to morphological data from a classical adaptive radiation (Greater Antillean Anolis lizards). We show that models that account for competition and geography perform better than other models. The matching competition model is an important new tool for studying the influence of interspecific interactions, in particular competition, on phenotypic evolution. More generally, it constitutes a step toward a better integration of interspecific

  19. Root pruning reduces root competition in living mulch cropping systems

    OpenAIRE

    Båth, B.; Kristensen, Hanne Lakkenborg; Thorup-Kristensen, Kristian

    2009-01-01

    In intercropping systems with a cash crop and a living mulch intercrop, competition between the cash crop and the intercrop (the living mulch) often reduces the yield of the cash crop. This project investigated (1) the influence of root pruning of living mulches on aboveground biomass of white cabbage. Below-ground growth and competition were examined by measuring (2) root distribution in minirhizotrons and (3) uptake of 15N placed at different soil depths. Two field experiments were carried ...

  20. Effects of Agricultural Pollutants on Competition Between Filter-Feeding Caddis Flies

    Science.gov (United States)

    Olsen, D. A.; Watzin, M. C.

    2005-05-01

    The effects of agricultural pollutants on competition between lotic macroinvertebrates are largely unstudied. We investigated how agricultural pollution affects competition between larvae of two caddis flies, Hydropsyche spp. and Brachycentrus appalachia. Month-long laboratory experiments were conducted in recirculating stream microcosms at two levels of Hydropsyche abundance: low density (80 Hydropsyche and 40 Brachycentrus per tank) and high density (300 Hydropsyche and 40 Brachycentrus). Experimental factors tested were agricultural pollutant addition (cow manure compost and sand) versus control tanks and taxon combination (Hydropsyche only, Brachycentrus only, and both taxa). In high-density experiments, mortality and drift of Hydropsyche were higher in agricultural tanks than in controls and more Brachycentrus drifted in tanks with Hydropsyche present. In low-density experiments, mortality of Brachycentrus was higher in tanks with Hydropsyche present. In both high and low-density experiments,Brachycentrus had lower mean condition (as measured by body-length residuals) in the presence ofHydropsyche, although these differences were only statistically significant in the high-density experiment. No difference in condition was observed for Hydropsyche at either density. Our results provide evidence of both competition between Hydropsyche and Brachycentrus and direct effects of pollutant addition, but the pollution effects did not alter the competitive interactions between the two species.

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

    Directory of Open Access Journals (Sweden)

    Ewert P.J. Kleynhans

    2014-02-01

    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.

  2. Factors affecting athletes’ motor behavior after the observation of scenes of cooperation and competition in competitive sport: the effect of sport attitude

    Directory of Open Access Journals (Sweden)

    Elisa eDe Stefani

    2015-10-01

    Full Text Available AbstractAim: This study delineated how observing sports scenes of cooperation or competition modulated an action of interaction, in expert athletes, depending on their specific sport attitude. Method: In a kinematic study, athletes were divided into two groups depending on their attitude towards teammates (cooperative or competitive. Participants observed sport scenes of cooperation and competition (basketball, soccer, water polo, volleyball, and rugby and then they reached for, picked up, and placed an object on the hand of a conspecific (giving action. Mixed-design ANOVAs were carried out on the mean values of grasping-reaching parameters. Results: Data showed that the type of scene observed as well as the athletes’ attitude affected reach-to-grasp actions to give. In particular, the cooperative athletes were speeded during reach-to-grasp movements when they observed scenes of cooperation compared to when they observed scenes of competition. Discussion: Participants were speeded when executing a giving action after observing actions of cooperation. This occurred only when they had a cooperative attitude. A match between attitude and intended action seems to be a necessary prerequisite for observing an effect of the observed type of scene on the performed action. It is possible that the observation of scenes of competition activated motor strategies which interfered with the strategies adopted by the cooperative participants to execute a cooperative (giving sequence.

  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. 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

  5. Effects of competitive interactions of different life forms submersed plants on biomass allocation in shallow lakes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiu-feng

    2010-01-01

    Plant competition has been recognized as one of the most important factors influencing the structure and function of lake ecosystems.Competition from plants of dissimilar growth form may have profound effects on shallow lakes.An experiment was conducted to investigate the effects of competitive interactions of submersed plants with dissimilar growth forms on the biomass allocations.Hydrilla verticillata and Vallisneria natans were selected and were planted in a single-species monoculture and a mixed-species pattern.Results showed that the growth of Ⅴ.natans was significantly affected by the H.verticillata and caused a sharp reduction of biomass,but the root:shoot ratio of Ⅴ.natans was not affected significantly and there was a minimal increase in mixture: while for H.verticillata,the biomass and the root:shoot ratio were not significantly changed by the competitive interactions of Ⅴ.natans,there was minimal increase qf biomass and minimal decrease of the root:shoot ratio.These results may indicate that the phant which candevelop a dense mat or canopy at the water surface would be a stronger competitor relative to the plant that dependsmore on light availability near the sediment.

  6. 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.

  7. The role of effective personnel management in enhancing the competitiveness of dairy systems: theory, practice, benchmarking

    OpenAIRE

    Tatyana Grydkina; Liliya Pechnikova

    2013-01-01

    At the present stage of development of the economy as an effective personnel management is of particular relevance in enhancing the competitiveness of dairy complexes. The main purpose of human resource management in the industry is molokoproizvodyaschey timely decisions that determine the human resources and the amount required to meet production goals, the selection of competent and motivated staff, the ability to retain them, organizing them effectively, improve worker training, social dev...

  8. The role of effective personnel management in enhancing the competitiveness of dairy systems: theory, practice, benchmarking

    Directory of Open Access Journals (Sweden)

    Tatyana Grydkina

    2013-04-01

    Full Text Available At the present stage of development of the economy as an effective personnel management is of particular relevance in enhancing the competitiveness of dairy complexes. The main purpose of human resource management in the industry is molokoproizvodyaschey timely decisions that determine the human resources and the amount required to meet production goals, the selection of competent and motivated staff, the ability to retain them, organizing them effectively, improve worker training, social development.

  9. Securitization, Competition and Monitoring.

    OpenAIRE

    Ahn, J-H; Breton, R.

    2013-01-01

    We analyze the impact of loan securitization on competition in the loan market. Using a dynamic loan market competition model where borrowers face both exogenous and endogenous costs to switch between banks, we uncover a competition softening effect of securitization that allows banks to extract rents in the primary loan market. By reducing monitoring incentives, securitization mitigates winner’s curse effects in future stages of competition thereby decreasing ex ante competition for initial ...

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

    International Nuclear Information System (INIS)

    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)

  11. Social behaviors as determined by different arrangements of social consequences: diffusion of responsibility effects with competition.

    Science.gov (United States)

    Guerin, Bernard

    2003-06-01

    According to a recently proposed synthesis, social loafing, social facilitation, and deindividuation can be viewed as different ways of arranging social consequences (B. Guerin, 1999). The effects of such arrangements have been measured in past research as productive output (social loafing and social facilitation) or as antinormative behaviors (deindividuation), but all 3 effects are manipulable by changing individual identifiability, evaluation, social identity, task difficulty, and presence in a group. The synthesis also predicted that these same variables would apply to other measures and other arrangements of social consequences. To this end, in the present 2 experiments, the author varied the arrangements for consequence diffusion in a competition situation by varying small and large competing groups and measured productive output and antinormative behaviors simultaneously. The 2 experiments showed social-consequence effects in competition situations with college students, giving further support for the social-consequence synthesis and the idea that the verbal naming of phenomena in social psychology is arbitrary. PMID:12846515

  12. Competitive effects of nuclear deformation and density dependence of $\\Lambda\\!N$ interaction

    CERN Document Server

    Isaka, M; Rijken, T h A

    2016-01-01

    Competitive effects of nuclear deformation and density dependence of $\\Lambda\\!N$-interaction in $\\Lambda$ binding energies $B_\\Lambda$ of hypernuclei are studied systematically on the basis of the baryon-baryon interaction model ESC including many-body effects. By using the $\\Lambda\\!N$ G-matrix interaction derived from ESC, we perform microscopic calculations of $B_\\Lambda$ in $\\Lambda$ hypernuclei within the framework of the antisymmetrized molecular dynamics under the averaged-density approximation. The calculated values of $B_\\Lambda$ reproduce experimental data within a few hundred keV in the wide mass regions from 9 to 51. It is found that competitive effects of nuclear deformation and density dependence of $\\Lambda\\!N$-interaction work decisively for fine tuning of $B_\\Lambda$ values.

  13. Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus.

    Directory of Open Access Journals (Sweden)

    Jeffrey Bara

    Full Text Available Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2 extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced.

  14. Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus.

    Science.gov (United States)

    Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E; Muturi, Ephantus J

    2015-01-01

    Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced. PMID:25951173

  15. Metabolomics in the Rhizosphere: Tapping into Belowground Chemical Communication.

    Science.gov (United States)

    van Dam, Nicole M; Bouwmeester, Harro J

    2016-03-01

    The rhizosphere is densely populated with a variety of organisms. Interactions between roots and rhizosphere community members are mostly achieved via chemical communication. Root exudates contain an array of primary and secondary plant metabolites that can attract, deter, or kill belowground insect herbivores, nematodes, and microbes, and inhibit competing plants. Metabolomics of root exudates can potentially help us to better understand this chemical dialogue. The main limitations are the proper sampling of the exudate, the sensitivity of the metabolomics platforms, and the multivariate data analysis to identify causal relations. Novel technologies may help to generate a spatially explicit metabolome of the root and its exudates at a scale that is relevant for the rhizosphere community.

  16. An exploitation-competition system with negative effect of prey on its predator.

    Science.gov (United States)

    Wang, Yuanshi

    2015-05-01

    This paper considers an exploitation-competition system in which exploitation is the dominant interaction when the prey is at low density, while competition is dominant when the prey is at high density due to its negative effect on the predator. The two-species system is characterized by differential equations, which are the combination of Lotka-Volterra competitive and predator-prey models. Global dynamics of the model demonstrate some basic properties of exploitation-competition systems: (i) When the growth rate of prey is extremely small, the prey cannot promote the growth of predator. (ii) When the growth rate is small, an obligate predator can survive by preying on the prey, while a facultative predator can approach a high density by the predation. (iii) When the growth rate is intermediate, the predator can approach the maximal density by an intermediate predation. (iv) When the growth rate is large, the predator can persist only if it has a large density and its predation on the prey is big. (v) Intermediate predation is beneficial to the predator under certain parameter range, while over- or under-predation is not good. Extremely big/small predation would lead to extinction of species. Numerical simulations confirm and extend our results. PMID:25707917

  17. 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. PMID:27062731

  18. An exploitation-competition system with negative effect of prey on its predator.

    Science.gov (United States)

    Wang, Yuanshi

    2015-05-01

    This paper considers an exploitation-competition system in which exploitation is the dominant interaction when the prey is at low density, while competition is dominant when the prey is at high density due to its negative effect on the predator. The two-species system is characterized by differential equations, which are the combination of Lotka-Volterra competitive and predator-prey models. Global dynamics of the model demonstrate some basic properties of exploitation-competition systems: (i) When the growth rate of prey is extremely small, the prey cannot promote the growth of predator. (ii) When the growth rate is small, an obligate predator can survive by preying on the prey, while a facultative predator can approach a high density by the predation. (iii) When the growth rate is intermediate, the predator can approach the maximal density by an intermediate predation. (iv) When the growth rate is large, the predator can persist only if it has a large density and its predation on the prey is big. (v) Intermediate predation is beneficial to the predator under certain parameter range, while over- or under-predation is not good. Extremely big/small predation would lead to extinction of species. Numerical simulations confirm and extend our results.

  19. 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.

  20. 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. PMID:27375630

  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. 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. PMID:27375630

  3. Materazzi effect and the strategic use of anger in competitive interactions.

    Science.gov (United States)

    Gneezy, Uri; Imas, Alex

    2014-01-28

    We propose that individuals use anger strategically in interactions. We first show that in some environments angering people makes them more effective in competitions, whereas in others, anger makes them less effective. We then show that individuals anticipate these effects and strategically use the option to anger their opponents. In particular, they are more likely to anger their opponents when anger negatively affects the opponents' performances. This finding suggests people understand the effects of emotions on behavior and exploit them to their advantage. PMID:24474756

  4. Effect of CO2 enrichment on competition between Skeletonema costatum and Heterosigma akashiwo

    Science.gov (United States)

    Xu, Da; Zhou, Bin; Wang, You; Ju, Qing; Yu, Qingyun; Tang, Xuexi

    2010-07-01

    We investigated the effect of CO2 enrichment and initial inoculum density on competition between Skeletonema costatum and Heterosigma akashiwo, two common algae seen in algal blooms. The initial inoculum density (0.2×104, 0.4×104, 0.8×104 cells/ml) had a significant effect on population growth and competition between H. akashiwo and S. costatum. The time required for population growth to reach the exponential growth phase and stationary phase decreased significantly as the initial density increased. When the two species were cultured together, S. costatum tended to outcompete H. akashiwo, especially when present at higher initial ratios. CO2 enrichment (5 000 μl/L CO2) increased the maximum population density and carrying capacity of H. akashiwo but decreased these measures for S. costatum. Thus, CO2 enrichment favored the growth of H. akashiwo over S. costatum.

  5. 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. PMID:25193551

  6. Investigating the Sensitivity of Equilibrium Profits to Advertising Dynamics and Competitive Effects

    OpenAIRE

    Pradeep K. Chintagunta

    1993-01-01

    The author investigates the validity of the "flat maximum principle"---the insensitivity of a firm's profits to changes in its optimal advertising level---in a duopolistic market in which advertising by the two firms has carryover effects. Two alternative competitive scenarios are examined (i) in which total industry sales are allowed to vary over time, and (ii) where firms are engaged in market share rivalry. For (i), the open-loop Nash equilibrium advertising strategies for the firms are de...

  7. The Effect of Export Tax on Indonesia’s Cocoa Export Competitiveness

    OpenAIRE

    Rifin, Amzul; Nauly, Dahlia

    2013-01-01

    The government of Indonesia implemented an export tax policy on cocoa beans since April 2010 in order to develop cocoa processing industry. The objective of this article is to analyze the effect of export tax on Indonesia’s cocoa export competitiveness. The results indicate that with the implementation of export tax, cocoa export product composition shift from cocoa beans to processed cocoa products. On the other hand, Indonesia’s cocoa export growth is lower than the growth of cocoa world de...

  8. Spillover and Competitive Effects of Advertising in the Carbonated Soft Drink Market

    OpenAIRE

    Rigoberto A. Lopez; Yizao Liu; Chen Zhu

    2013-01-01

    This paper examines the spillover effects of television advertising on brand-level consumer demand for carbonated soft drinks (CSDs) and the competition consequences for manufacturers’ and private label CSDs. Using a random coefficients logit model (BLP) with household purchasing and advertising viewing data from five U.S. cities, we find that although brand advertising is important in increasing demand as previous work confirms, company advertising spillovers are nearly as important. Not sur...

  9. Pro-competitive effects and harmful trade liberalization in multi-country world

    OpenAIRE

    Igor Bykadorov; Andrea Ellero; Stefania Funari; Sergey Kokovin; Pavel Molchanov

    2015-01-01

    We study a multi-country trade model with two types of countries (big and small ones). The model generalizes the case of two countries analyzed in [3] and wonder whether there could be harm from trade. Monopolistic competition, iceberg type trade costs and variable elasticity of substitution (VES) are among the model assumptions. The effects of trade liberalization on price, production and welfare are analyzed, in cases of free trade and autarky.

  10. The Performance Effects of Congruence Between Product Competitive Strategies and Purchasing Management Design

    OpenAIRE

    Julie Smith David; Yuhchang Hwang; Buck K. W. Pei; J. Hal Reneau

    2002-01-01

    The objective of this study is to examine a performance contingency effect between product competitive strategy and organization design using an archival approach. Specifically, this study examines a sample of 194 firms from 20 industries based on the data collected by Center for Advanced Purchasing Studies (CAPS) in its benchmarking surveys between 1989-1994 and links the benchmarking data to the COMPUSTAT (Standard & Poor's) financial data of these firms. The results of the study reveal a c...

  11. Competition of Brazil nut effect, buoyancy, and inelasticity induced segregation in a granular mixture

    OpenAIRE

    Brito López, Ricardo; Soto, R.

    2009-01-01

    It has been recently reported that a granular mixture in which grains differ in their restitution coefficients presents segregation: the more inelastic particles sink to the bottom. When other segregation mechanisms as buoyancy and the Brazil nut effect are present, the inelasticity induced segregation can compete with them. First, a detailed analysis, based on numerical simulations of two dimensional systems, of the competition between buoyancy and the inelasticity induced segregation is pre...

  12. Cross-diffusional effect in a telegraph reaction diffusion Lotka-Volterra two competitive system

    Energy Technology Data Exchange (ETDEWEB)

    Abdusalam, H.A E-mail: hosny@operamail.com; Fahmy, E.S

    2003-10-01

    It is known now that, telegraph equation is more suitable than ordinary diffusion equation in modelling reaction diffusion in several branches of sciences. Telegraph reaction diffusion Lotka-Volterra two competitive system is considered. We observed that this system can give rise to diffusive instability only in the presence of cross-diffusion. Local and global stability analysis in the cross-diffusional effect are studied by considering suitable Lyapunov functional.

  13. Oil Price Effects on Land Use Competition – An Empirical Analysis

    OpenAIRE

    Diermeier, Matthias; Schmidt, Torsten

    2012-01-01

    The increasing use of food commodities for biofuel production has substantial impact on prices and quantities of these and other food commodities. It is therefore likely that this trend also intensifies the competition for arable land. However, evidence for this hypothesis is generated by calibrated models while empirical evidence is rare. In this paper we analyze the effects of crude oil price and prices of input factors for biofuel production on prices, areas and quantities of selected food...

  14. Effect of multiple-source entry on price competition after patent expiration in the pharmaceutical industry.

    OpenAIRE

    Suh***, D.C.; Manning, W G; Schondelmeyer, S; Hadsall, R S

    2000-01-01

    OBJECTIVE: To analyze the effect of multiple-source drug entry on price competition after patent expiration in the pharmaceutical industry. DATA SOURCES: Originators and their multiple-source drugs selected from the 35 chemical entities whose patents expired from 1984 through 1987. Data were obtained from various primary and secondary sources for the patents' expiration dates, sales volume and units sold, and characteristics of drugs in the sample markets. STUDY DESIGN: The study was designed...

  15. Effects of soil organic matter and nitrogen supply on competition between Fectuca ovina and Deschampsia flexuosa during inland dune succession

    NARCIS (Netherlands)

    Mierlo, van J.E.M.; Wilms, Y.J.C.; Berendse, F.

    2000-01-01

    We tested the prediction that the successional replacement of plant species during succession on inland sand dunes results from the effects of an increase in nitrogen mineralization on competitive interactions. The growth and competitive strength of Festuca ovina and Deschampsia flexuosa on soil sub

  16. Ionization competition effects on population distribution and radiative opacity of mixture plasmas

    International Nuclear Information System (INIS)

    Ionization competition arising from the electronic shell structures of various atomic species in the mixture plasmas was investigated, taking SiO2 as an example. Using a detailed-level-accounting approximation, we studied the competition effects on the charge state population distribution and spectrally resolved and Planck and Rosseland mean radiative opacities of mixture plasmas. A set of coupled equations for ionization equilibria that include all components of the mixture plasmas are solved to determine the population distributions. For a given plasma density, competition effects are found at three distinct temperature ranges, corresponding to the ionization of M-, L-, and K-shell electrons of Si. Taking the effects into account, the spectrally resolved and Planck and Rosseland mean opacities are systematically investigated over a wide range of plasma densities and temperatures. For a given mass density, the Rosseland mean decreases monotonically with plasma temperature, whereas Planck mean does not. Although the overall trend is a decrease, the Planck mean increases over a finite intermediate temperature regime. A comparison with the available experimental and theoretical results is made

  17. Competitive displacement between two invasive whiteflies: insecticide application and host plant effects.

    Science.gov (United States)

    Sun, Di-Bing; Liu, Yin-Quan; Qin, Li; Xu, Jing; Li, Fang-Fang; Liu, Shu-Sheng

    2013-06-01

    The cryptic species Middle East-Asia Minor 1 (MEAM1), formerly referred to as 'B biotype', of the whitefly Bemisia tabaci complex entered China in the mid 1990s, and the Mediterranean (MED) cryptic species, formerly referred to as 'Q biotype', of the same whitefly complex entered China around 2003. Field surveys in China after 2003 indicate that in many regions MED has been replacing the earlier invader MEAM1. The factors underlying this displacement are unclear. We conducted laboratory experiments and field sampling to examine the effects of insecticide application on the competitive interactions between MEAM1 and MED. In the laboratory, on cotton, a plant showing similar levels of suitability to both whitefly species, MEAM1 displaced MED in five generations when initial populations of the two species were equal and no insecticide was applied. In contrast, MED displaced MEAM1 in seven and two generations, respectively, when 12.5 and 50.0 mg l⁻¹ imidacloprid was applied to the plants via soil drench. Field sampling indicated that in a single season MED displaced MEAM1 on crops heavily sprayed with neonicotinoid insecticides but the relative abundance of the two species changed little on crops without insecticide spray. We also examined the effects of host plants on the competitive interactions between the two species in the laboratory. When cohorts with equal abundance of MEAM1 and MED were set up on different host plants, MEAM1 displaced MED on cabbage and tomato in five and seven generations, respectively, but MED displaced MEAM1 on pepper in two generations. As field populations of MED have lower susceptibility than those of MEAM1 to nearly all commonly used insecticides including imidacloprid, insecticide application seems to have played a major role in shifting the species competitive interaction effects in favour of MED in the field across China. Host plants may also shape competition between the two species depending on the relative levels of plant

  18. How can we exploit above-belowground interactions to assist in addressing the challenges of food security?

    Science.gov (United States)

    Orrell, Peter; Bennett, Alison E

    2013-10-30

    Can above-belowground interactions help address issues of food security? We address this question in this manuscript, and review the intersection of above-belowground interactions and food security. We propose that above-belowground interactions could address two strategies identified by Godfray etal. (2010): reducing the Yield Gap, and Increasing Production Limits. In particular, to minimize the difference between potential and realized production (The Yield Gap) above-belowground interactions could be manipulated to reduce losses to pests and increase crop growth (and therefore yields). To Increase Production Limits we propose two mechanisms: utilizing intercropping (which uses multiple aspects of above-belowground interactions) and breeding for traits that promote beneficial above-belowground interactions, as well as breeding mutualistic organisms to improve their provided benefit. As a result, if they are managed correctly, there is great potential for above-belowground interactions to contribute to food security.

  19. Raman probing of competitive laser heating and local recrystallization effect in ZnO nanocrystals.

    Science.gov (United States)

    Ye, J D; Parkinson, P; Ren, F F; Gu, S L; Tan, H H; Jagadish, C

    2012-10-01

    The competitive laser-induced local heating and recrystallization effects in ZnO nanocrystals embedded in a MgO/ZnO stack are reported via resonance Raman spectra. The dependence of the intensity, energy, and resonance effects of the longitudinal optical (LO) phonon on laser excitation condition are discussed in the context of Fröhlich interaction. Redistribution of defects, impurity-diffusion, and grain regrowth caused by thermal and photochemical effects lead to significant changes in coupling strength of electron-phonon interaction, and the resonance behaviors are strongly affected by the interplay of local heating, heat trapping, and local structural modification in such nanostructures.

  20. Effects of competition on great and blue tit reproduction: intensity and importance in relation to habitat quality.

    Science.gov (United States)

    Dhondt, André A

    2010-01-01

    1. In studies on the effect of competition in plant communities two terms are used to describe its effects: the absolute reduction in growth of an individual as a consequence of the presence of another one is called intensity, while the relative impact of competition on an individual as a proportion of the impact of the whole environment is called importance. One school of thought is that the role of competition remains constant across productivity gradients, while the other is that it decreases with increasing severity. J.B. Grace (1991. A clarification of the debate between grime and tilman. Functional Ecology, 5, 583-587.) suggested that the apparent contradiction might be solved if we acknowledge that the two schools are discussing different aspects of competition: the intensity of competition might remain constant while its importance declines with increasing severity. 2. There are no studies that compare intensity and importance of competition in bird populations between areas that differ in quality or productivity and hence it is not possible to make predictions how intensity or importance of competition would vary between them. 3. I compared variation in intensity and importance of competition of three demographic variables between five plots that differ strongly in quality for great Parus major L. and blue tit Cyanistes caeruleus (L.). 4. Both intensity and importance of competition are larger in great than in blue tit populations meaning that the effect of competition on demographic variables is stronger in great than in blue tits and that the contribution of competition to variation in these variables is relatively higher in great than in blue tits. 5. Intensity of competition is higher in low quality than in high quality plots for both species, a result not expected from studies in plant communities. 6. Importance of competition varies strongly between plots. It is larger in oak-dominated plots than in mixed deciduous plots. 7. In birds breeding density

  1. 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.

  2. Are patterns in nutrient limitation belowground consistent with those aboveground: Results from a 4 million year chronosequence

    Science.gov (United States)

    Reed, S.C.; Vitousek, P.M.; Cleveland, C.C.

    2011-01-01

    Accurately predicting the effects of global change on net carbon (C) exchange between terrestrial ecosystems and the atmosphere requires a more complete understanding of how nutrient availability regulates both plant growth and heterotrophic soil respiration. Models of soil development suggest that the nature of nutrient limitation changes over the course of ecosystem development, transitioning from nitrogen (N) limitation in 'young' sites to phosphorus (P) limitation in 'old' sites. However, previous research has focused primarily on plant responses to added nutrients, and the applicability of nutrient limitation-soil development models to belowground processes has not been thoroughly investigated. Here, we assessed the effects of nutrients on soil C cycling in three different forests that occupy a 4 million year substrate age chronosequence where tree growth is N limited at the youngest site, co-limited by N and P at the intermediate-aged site, and P limited at the oldest site. Our goal was to use short-term laboratory soil C manipulations (using 14C-labeled substrates) and longer-term intact soil core incubations to compare belowground responses to fertilization with aboveground patterns. When nutrients were applied with labile C (sucrose), patterns of microbial nutrient limitation were similar to plant patterns: microbial activity was limited more by N than by P in the young site, and P was more limiting than N in the old site. However, in the absence of C additions, increased respiration of native soil organic matter only occurred with simultaneous additions of N and P. Taken together, these data suggest that altered nutrient inputs into ecosystems could have dissimilar effects on C cycling above- and belowground, that nutrients may differentially affect of the fate of different soil C pools, and that future changes to the net C balance of terrestrial ecosystems will be partially regulated by soil nutrient status. ?? 2010 US Government.

  3. Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield

    OpenAIRE

    Wajja-Musukwe, Tellie-Nelson; Wilson, Julia; Sprent, Janet I.; Ong, Chin K.; Deans, J. Douglas; Okorio, John

    2008-01-01

    Tree root pruning is a potential tool for managing below-ground competition when trees and crops are grown together in agroforestry systems. This study investigates its effects on growth and root distribution of Alnus acuminata (HB & K), Casuarina equisetifolia (L), Grevillea robusta (A. Cunn. ex R. Br), Maesopsis eminii (Engl.), and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most spec...

  4. The effect of public intervention on global competitiveness and foreign direct investment: The case of Turkey

    Directory of Open Access Journals (Sweden)

    Coşkun Karaca

    2014-04-01

    Full Text Available Nowadays, competitive power has become an important indicator of success in international area. In order to become an important actor in global level, it is possible for the countries to use their political apparatus and to increase the number of the industries with high added value in the market via directive policies. Accordingly, foreign direct investments, which have high technology and innovation qualification, are encouraged by the countries to invest in their territory. In this study; it is tried to measure the effects of the public interference, carried out in 28 countries between 1996 and 2011, on foreign direct investments and competitive power of the countries by using panel data analysis. The results of the study showed that educational level and research development capacity encourages foreign direct investment inputs, on the contrary high levels of tax rate prevents these investments. Besides, some findings have been reached which indicates that present foreign direct investments operating in the country has a positive effect on competitive power.

  5. UK's climate change levy: cost effectiveness, competitiveness and environmental impacts

    Energy Technology Data Exchange (ETDEWEB)

    Varma, Adarsh [Hull Univ., School of Economic Studies, Hull (United Kingdom)

    2003-01-01

    This paper intends to examine the cost effectiveness of UK's climate change levy (CCL), its implications on competitiveness of firms and the environmental impact. The paper briefly describes the levy and analyses it under the canons of a good taxation policy. The economic implications of the levy are discussed with theoretical and empirical perspectives. Change in net exports, investment patterns and productivity and inclusion of compliance cost forms the basis for analysing the effect on competitiveness. It discusses the options available to firms to safeguard their competitiveness if it is adversely affected by the CCL. A description of the current scenario of the levy since its inception is also presented. The paper argues the need for a comprehensive policy involving the use of standards, emission trading as well as energy taxes to achieve emission and energy-use reductions. A focal point of this paper is to elucidate the pros and cons of the CCL (energy tax) with respect to an emission trading scheme. (Author)

  6. Effects of Competition and Cooperation Interaction between Agents on Networks in Presence of a "Market Capacity"

    CERN Document Server

    Sonubi, A; Stefani, S; Ausloos, M

    2016-01-01

    A network effect is introduced taking into account competition, cooperation and mixed-type interaction amongst agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity enforces an indubious 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 amongst 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.

  7. Competitive versus cooperative attitudes in crossed categorization effects: testing the category dominance and equivalence models.

    Science.gov (United States)

    Singh, Ramadhar; Poh, Woon Ying; Chang, Anthony P M

    2008-02-01

    Participants' (N = 256) competitive or cooperative attitudes toward national groups were activated by their reading 1 of 2 selected newspaper articles. Participants then judged the competence and attractiveness of a stranger who was categorized, separately for race and nationality, as belonging to an out-group or in-group. As predicted, the activated competitive attitude produced responses prescribed by the model of category dominance by nationality. In the condition of cooperative attitudes, however, competence responses were consistent with the model of equivalence (i.e., no effect of category) and attraction responses were consistent with the model of category dominance by race. The authors discuss reasons for the discrepant models in the condition of cooperative attitudes and the implications of these findings. PMID:18476480

  8. Effect of UV-B irradiation on interspecific competition between Ulva pertusa and Grateloupia filicina

    Institute of Scientific and Technical Information of China (English)

    李丽霞; 张培玉; 赵吉强; 周文礼; 唐学玺

    2010-01-01

    We report the effect of UV-B irradiation(9.6 kJ m-2day-1)on interspecific competition between two species of macroalgae,Ulva pertusa(U)and Grateloupia filicina(G),in co-culture.Growth of U.pertusa and G.filicina was inhibited by UV-B irradiation in mono-culture and specific growth rate (μ)declined as a result.Interspecific competition between U.pertusa and G.filicina was closely related to the initial weights when co-cultured.When initial ratios of U.pertusa(U)to G.filicina(G)were U:G=1.2:1 and 1:1,U.pertus...

  9. Seating Arrangement, Group Composition and Competition-driven Interaction: Effects on Students' Performance in Physics

    International Nuclear Information System (INIS)

    We probe the effect of seating arrangement, group composition and group-based competition on students' performance in Physics using a teaching technique adopted from Mazur's peer instruction method. Ninety eight lectures, involving 2339 students, were conducted across nine learning institutions from February 2006 to June 2009. All the lectures were interspersed with student interaction opportunities (SIO), in which students work in groups to discuss and answer concept tests. Two individual assessments were administered before and after the SIO. The ratio of the post-assessment score to the pre-assessment score and the Hake factor were calculated to establish the improvement in student performance. Using actual assessment results and neural network (NN) modeling, an optimal seating arrangement for a class was determined based on student seating location. The NN model also provided a quantifiable method for sectioning students. Lastly, the study revealed that competition-driven interactions increase within-group cooperation and lead to higher improvement on the students' performance.

  10. Competition effect of some metal ions on the complexation of strontium with humic acid. Vol. 4

    International Nuclear Information System (INIS)

    Interaction of radioactive strontium with humic acid present in water streams is of main importance to learn about the fate of strontium in case of accidental release. In this work, formation of Sr-humate precipitate was studied radiometrically and colorimetric at different PH's. The investigations indicated that formation of the precipitated complex increases with increasing strontium concentration till saturation. The competition effect of other cations in solution such as Ca, Mg, Ba, and Ni was investigated. The humate complexes of these cations were studied colorimetric, and the competition behaviour was investigated using the radiotracer of strontium. The results indicated that presence of Ba, Mg and Ni decreases the Sr-humate complex, while increasing Ca concentration enhances precipitation of Sr with humic acid. 10 figs

  11. Seating Arrangement, Group Composition and Competition-driven Interaction: Effects on Students' Performance in Physics

    Science.gov (United States)

    Roxas, R. M.; Carreon-Monterola, S. L.; Monterola, C.

    2010-07-01

    We probe the effect of seating arrangement, group composition and group-based competition on students' performance in Physics using a teaching technique adopted from Mazur's peer instruction method. Ninety eight lectures, involving 2339 students, were conducted across nine learning institutions from February 2006 to June 2009. All the lectures were interspersed with student interaction opportunities (SIO), in which students work in groups to discuss and answer concept tests. Two individual assessments were administered before and after the SIO. The ratio of the post-assessment score to the pre-assessment score and the Hake factor were calculated to establish the improvement in student performance. Using actual assessment results and neural network (NN) modeling, an optimal seating arrangement for a class was determined based on student seating location. The NN model also provided a quantifiable method for sectioning students. Lastly, the study revealed that competition-driven interactions increase within-group cooperation and lead to higher improvement on the students' performance.

  12. Effects of stress on defensive aggression and dominance in a water competition test.

    Science.gov (United States)

    Lucion, A; Vogel, W H

    1994-01-01

    Water-deprived rats in a pair competing for a single source of water quickly establish a firm relationship during which one rat drinks consistently more (dominant) than the other (submissive) animal. This relationship is formed during the first competition and is very stable during subsequent tests. Exposure of dominant rats to a severe (18 hrs immobilization), but not a mild (2 hrs immobilization), stressor reduced markedly aggressive behavior and inverted transiently the dominant submissive relationship of the pairs. Exposure of submissive rats to the severe stressor resulted in only minor reductions of aggressive behavior in these animals. Prestress anxiety predicted stress effects in the dominant animals in that high-anxious animals lost more dominant behavior and weight during stress as compared with low-anxious rats. Thus, severe stress can transiently reduce dominant but not submissive behavior during water competition and high-anxious rats are more prone to lose their aggressive behavior. PMID:7696138

  13. Globalization and the effects of national versus international competition on the labour market. Theory and evidence from Belgian firm level data

    OpenAIRE

    Vandenbussche, Hylke; Konings, Joep

    1998-01-01

    In this paper we first develop a simple theoretical framework which shows that important differences exist between national and international competition and their effect on national labour markets. National competition refers to a reduction of monopoly power in the product market through improved market contestability and market access, which is the responsibility of competition authorities. International competition refers to a reduction in product market competition as a result of trade li...

  14. 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.

  15. Effects of random motility on microbial growth and competition in a flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ballyk, M.; Dung, L.; Jones, D.A.; Smith, H.L. [Arizona State Univ., Tempe, AZ (United States). Dept. of Mathematics

    1998-11-01

    The authors investigate the effects of random motility on the ability of a microbial population to survive in pure culture and to be a good competitor for scarce nutrient in mixed culture in a flow reactor model consisting of a nonlinear parabolic system of partial differential equations. For pure culture (*a single population), a sharp condition is derived which distinguishes between the two outcomes: (1) washout of the population from the reactor or (2) persistence of the population and the existence of a unique single-population steady state. The simulations suggest that this steady state is globally attracting. For the case of two populations competing for scarce nutrient, they obtain sufficient conditions for the uniform persistence of the two populations, for the existence of a coexistence steady state, and for the ability of one population to competitively exclude a rival. Extensive simulations are reported which suggest that (1) all solutions approach some steady state solution, (2) all possible outcomes exhibited by the classical competitive Lotka-Volterra ODE model can occur in the model, and (3) the outcome of competition between two bacterial strains can depend rather subtly on their respective random motility coefficients.

  16. [Effects of nutritional condition on the competitive parameters of Prorocentrum donghaiense and Skeletonema costatum].

    Science.gov (United States)

    Wang, Fang; Ge, Wei; Chai, Chao; Wang, Jin-Ye; Zhao, Xiu-Fen

    2012-05-01

    By the methods of pure culture and mixed culture in laboratory, this paper studied the effects of different substrate nitrogen and phosphorus concentrations on the population growth and interspecific competitive parameters of two kinds of microalgae, Skeletonema costatum and Prorocentrum donghaiens. With the increasing concentrations of substrate nitrogen and phosphorus, the maximum biomass of the two kinds of microalgae increased, and their specific growth rate was higher in pure culture than in mixed culture. In mixed culture, S. costatum was dominant at the beginning, while P. donghaiense became dominant later. The time period when this change happened was related to the nutritional conditions, and the inflection point for S. costatum and P. donghaiense was about 0-2.6 and 0.5-4.9 d, respectively. Under the test nutritional conditions, the competitive parameter of P. donghaiense to S. costatum (beta) was higher than that of S. costatum to P. donghaiense (alpha). When the substrate nitrogen and phosphorous concentrations were 128 micromol N x L(-1) and 32 micromol P x L(-1), the competitive capability of P. donghaiense was 3.8 times of that of S. costatum, presenting the most obvious difference. PMID:22919854

  17. -selection, -selection, effectiveness, and tolerance in competition: density-dependent selection revisited

    Indian Academy of Sciences (India)

    Amitabh Joshi; N. G. Prasad; Mallikarjun Shakarad

    2001-08-01

    In the Drosophila literature, selection for faster development and selection for adapting to high density are often confounded, leading, for example, to the expectation that selection for faster development should also lead to higher competitive ability. At the same time, results from experimental studies on evolution at high density do not agree with many of the predictions from classical density-dependent selection theory. We put together a number of theoretical and empirical results from the literature, and some new experimental results on Drosophila populations successfully subjected to selection for faster development, to argue for a broader interpretation of density-dependent selection. We show that incorporating notions of -selection, and the division of competitive ability into effectiveness and tolerance components, into the concept of density-dependent selection yields a formulation that allows for a better understanding of the empirical results. 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.

  18. Effects of fertility, weed density and crop competition on biomass partitioning in Centaurea cyanus L.

    Directory of Open Access Journals (Sweden)

    Łukasz Chachulski

    2014-02-01

    Full Text Available The influence of environmental factors on biomass partitioning of annual arable weed Centaurea cyanus was analysed. We investigated the effect of fertilisation, density and competition with the winter rye crop on the reproductive investment. Three fertiliser treatments and three density levels were applied. In Centaurea cyanus differences in the pattern of biomass allocation to reproduction are related to plant size. The relationship between reproductive and vegetative mass is close to linear. It is consistent with the model of linear size-dependent reproductive output. In Centaurea cyanus this model worked well for size differences that have been generated by interspecific competition, nutrients supply and density. Our data support the hypothesis that plastic changes in relationship between vegetative and generative biomass are environmentally-induced. Significantly different relationship between vegetative and reproductive biomass were detected among populations growing at different density and fertility levels. The fertilisation with mineral fertiliser and manure resulted in an increase of generative biomass allocated to flowerheads and a decrease of reproductive effort. Generative dry weight increased more rapidly with plant size in higher densities of population and at lower fertility levels. The experiment showed that the rate of weight allocated to reproductive structures was bigger under the pressure of competition with cereal crop. At low fertility level and high density, when the individuals were small, generative biomass increased faster with plant size. The production of seeds was not directly dependent on biomass allocated into total reproductive structures. At low level, of nutrient supply C. cyanus gave more offspring per gram of its biomass. We discuss the results in context of life-history theory. From the strategic point of view, size-dependent variation in reproductive effort and in efficiency of reproduction can be

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

    International Nuclear Information System (INIS)

    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

  20. 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. PMID:23669543

  1. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests

    OpenAIRE

    McIntosh, Anne C. S.; Ellen Macdonald, S.; Sylvie A Quideau

    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 f...

  2. Below-ground herbivory in natural communities: a review emphasizing fossorial animals

    Science.gov (United States)

    Andersen, Douglas C.

    1987-01-01

    Roots, bulbs, corms, and other below-ground organs are almost universally present in communities containing vascular plants. A large and taxonomically diverse group of herbivores uses these below-ground plant parts as its sole or primary source of food. Important within this group are plant-parasitic nematodes and several fossorial taxa that affect plants through their soil-disturbing activities as well as by consuming plant tissue. The fossorial taxa are probably best exemplified by fossorial rodents, which are distributed on all continents except Australia. All other fossorial herbivores are insects. The impact of below-groud herbivory on individual plant fitness will depend upon the extent to which, and under what circumstances, the consumption of plant tissue disrupts one or more of the six functions of below-ground plant parts. Below-ground herbivory is probably more often chronic than acute. Indirect evidence suggests that plants have responded evolutionarily to herbivory by enhancing the functional capacities of below-ground organs, thus developing a degree of tolerance, and by producing compounds that serve as feeding deterrents. Many plant species respond to the removal of root tissues by increasing the growth rate of the remaining roots and initiating new roots. Soil movement and mixing by fossorial rodents infleuce the environment of other below-ground herbivores as well as that of plants and plant propagules. The relationships among the various groups of below-ground herbivores, and between below-ground herbivores and plants, are at best poorly known, yet they appear to have major roles in determining the structure and regulating the functioning of natural communities.

  3. Uncertainty in below-ground carbon biomass for major land covers in Southeast Asia

    OpenAIRE

    Yuen, Jia Qi; Ziegler, Alan D.; Edward L Webb; Ryan, Casey M.

    2013-01-01

    Owing to difficulties associated with measuring root biomass accurately in space and time, below-ground root biomass is often calculated indirectly from above-ground biomass measurements via general allometric equations. Of concern is that general equations may not provide accurate site-specific calculations for accurate carbon stock assessments. This review comparing more than 100 root-related studies conducted in SE Asia shows highly variable and uncertain below-ground woody carbon (BGC) bi...

  4. Aboveground to belowground herbivore defense signaling in maize

    Science.gov (United States)

    Gill, Torrence; Zhu, Lixue; Lopéz, Lorena; Pechanova, Olga; Shivaji, Renuka; Ankala, Arunkanth; Williams, W. Paul

    2011-01-01

    Insect pests that attempt to feed on the caterpillar-resistant maize genotype Mp708 encounter a potent, multipronged defense system that thwarts their invasion. First, these plants are on “constant alert” due to constitutively elevated levels of the phytohormone jasmonic acid that signals the plant to activate its defenses. The higher jasmonic acid levels trigger the expression of defense genes prior to herbivore attack so the plants are “primed” and respond with a faster and stronger defense. The second defense is the rapid accumulation of a toxic cysteine protease called Mir1-CP in the maize whorl in response to caterpillar feeding. When caterpillars ingest Mir1-CP, it damages the insect's midgut and retards their growth. In this article, we discuss a third possible defense strategy employed by Mp708. We have shown that foliar caterpillar feeding causes Mir1-CP and defense gene transcripts to accumulate in its roots. We propose that caterpillar feeding aboveground sends a signal belowground via the phloem that results in Mir1-CP accumulation in the roots. We also postulate that the roots serve as a reservoir of Mir1-CP that can be mobilized to the whorl in response to caterpillar assault. PMID:21270535

  5. The effect of competition between two spatially separated markets - An investigation of two interlinked Bak-Sneppen models

    OpenAIRE

    Damgaard, Martin

    2008-01-01

    This paper investigates the effect of competition in a market consisting of interlinked economic agents. In particular, the effect of increased competition from the surrounding markets is demonstrated. The presented work is an extension of the Bak-Sneppen model (Bak and Sneppen 1993). Here are two Bak-Sneppen models interlinked such that if the lowest fitness value of one market exceeds the fitness values of the other market minus transportation cost, all cells lower than this band will recei...

  6. Regulation of mergers by the UK competition authorities: the effects on shareholder value and management motivations for mergers

    OpenAIRE

    Arnold, Malcolm F.

    2007-01-01

    The UK competition authorities are responsible for regulating company mergers that were originally considered to have adverse effects that were “against the public interest”, or presently that could result in a “substantial lessening of competition”. The research in this thesis examines wider economic side effects of this regulatory policy that fall outside the remit of the competition authorities. Data on 63 merger cases that were subject to the merger regulatory process by th...

  7. 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.

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

    International Nuclear Information System (INIS)

    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

  9. Responses of aboveground and belowground forest carbon stocks to disturbances in boreal forests of Northeastern China

    Science.gov (United States)

    Huang, Chao; He, Hong S.; Hawbaker, Todd J.; Liang, Yu; Gong, Peng; Wu, Wuzhiwei; Zhu, Zhiliang

    2016-04-01

    Boreal forests represents about 1/3 of forest area and 1/3 of forest carbon on earth. Carbon dynamics of boreal forests are sensitive to climate change, natural (e.g., fire) and anthropogenic (e.g., harvest) disturbances. Field-based studies suggest that disturbances alter species composition, stand structure, and litter decomposition, and have significant effects on boreal forest carbon dynamics. Most of these studies, however, covered a relatively short period of time (e.g., few decades), which is limited in revealing such long-term effects of disturbances. Models are therefore developed as important tools in exploring the long-term (e.g., hundreds of years) effects of disturbances on forest carbon dynamics. In this study, we applied a framework of coupling forest ecosystem and landscape model to evaluating the effect of fire, harvest and their interactions on carbon stocks in a boreal forest landscape of Northeastern China. We compared the simulation results under fire, harvest and fire-harvest interaction scenarios with the simulated value of succession scenario at 26 landtypes over 150 years at a 10-year time step. Our results suggest that aboveground and belowground carbon are significantly reduced by fire and harvest over 150years. Fire reduced aboveground carbon by 2.3±0.6 ton/ha, harvest by 6.0±1.4 ton/ha, and fire and harvest interaction by 8.0±1.9 tons/ha. Fire reduced belowground carbon by 4.6±3.4 ton/ha, harvest by 5.0±3.5 ton/ha, and fire-harvest interaction by 5.7±3.7 tons/ha. The divergent response of carbon stocks among landtypes and between disturbance scenarios was due to the spatial interactions between fire, harvest, and species composition. Our results indicated that boreal forests carbon stocks prediction needs to consider the effects of fire and harvest for improving the estimation accuracy.

  10. 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.

  11. Effects of small spatial variation of the reproduction rate in a two species competition model

    Directory of Open Access Journals (Sweden)

    Georg Hetzer

    2010-11-01

    Full Text Available Of concern is the effect of a small spatially inhomogeneous perturbation of the reproduction rate of the first species in a two-species Lotka-Volterra competition-diffusion problem with spatially homogeneous reaction terms. Apart from this perturbation and the diffusion rates, the two species are assumed to be identical. Our main result shows that the first species can always invade, whereas the second species can only invade under certain conditions which yield uniform persistence of both species. The proof relies on comparison techniques and properties of the principal eigenvalue of reaction-diffusion equations.

  12. Welfare Effects of Tariff Peak Conversion: The Case of Monopolistic Competition

    DEFF Research Database (Denmark)

    Schröder, Philipp; Jørgensen, Jan Guldager

    dispersion in initial tariffs (tariff peaks) and gaps between bound and applied tariff rates. This paper presents a general equilibrium model with monopolistic competition to examine the welfare effects of different formulas in a process of improving market access. Products with initially high and low...... tariffs are analyzed. It is established that reduction in the trade restriction using three formulas proposed in the literature i) a proportional cut, ii) the Swiss formula and iii) a compression formula leads to non-trivial impacts on the welfare....

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

    Directory of Open Access Journals (Sweden)

    P. Priault

    2011-02-01

    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 objectives of our study were 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 tunable 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. Seasonal patterns of carbon allocation to soil CO2 efflux differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with other sinks (aboveground growth in late spring and storage in late summer that were not observed in oak.

  14. 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.

  15. 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. PMID:24935641

  16. Competitiveness and Effects of Policies on Plantain Production Systems in Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    I. B. Adeoye

    2014-12-01

    Full Text Available Plantain is one of the most important staple crops in Nigeria and has the potential to contribute to food security and economic development of the country. There is inadequate information on competitiveness, comparative advantage and effects of government policies on the commodity. The study therefore analyzed competitiveness and effects of government policies on plantain production systems in Southwestern Nigeria. Primary data were collected using structured questionnaire from 260 producers randomly selected from major production areas in the zone. Secondary data on port charges and world prices were also utilized. Data were analyzed using Policy Analysis Matrix (PAM. Results indicated that plantain production was privately and socially profitable in all the productions systems. Domestic resource cost ratio of 0.16 – 0.19 and social cost benefit ratio of 0.20-0.23 revealed that southwestern Nigeria had comparative advantage in the production of the commodity. The policy indicators and incentives structure such as the nominal protection coefficient on output (0.31-0.42 and input (1.02-1.04, effective protection coefficient (0.26-0.37, profitability coefficient (0.21- 0.32, subsidy ratio to produces (-0.51 to -0.62 and producers subsidy estimate (-1.70 to -2.02 showed that the producers were taxed and there exists transfers of resources from the systems. The study recommends formulation of policies which are consistent with the country’s goals of agricultural transformation, food security and economic development.

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

    International Nuclear Information System (INIS)

    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

  18. Belowground Biomass Sampling to Estimate Fine Root Mass across NEON Sites

    Science.gov (United States)

    Spencer, J. J.; Meier, C. L.; Abercrombie, H.; Everhart, J. C.

    2013-12-01

    Production of belowground biomass is an important and relatively uncharacterized component of the net primary productivity (NPP) of ecosystems. Fine root productivity makes up a significant portion of total belowground production because fine roots turn over rapidly, and therefore contribute disproportionately to annual estimates of belowground net primary productivity (BNPP). One of the major goals of the National Ecological Observatory Network (NEON) is to quantify above- and below-ground NPP at 60 sites within 20 different eco-climactic regions. NEON's Terrestrial Observation System will carry out belowground biomass sampling throughout the life of the observatory to estimate fine root production. However, belowground biomass sampling during NEON operations will be constrained to a maximum depth of 50cm. This limited depth range leaves the question of what proportion of total fine root mass is being collected and how to optimally characterize belowground biomass given sampling depth limitations. During the construction period, NEON is characterizing fine root biomass distribution at depth down to 2m at each site, as well as physical and chemical properties in each soil horizon. Each sampling unit is a pit (2m deep and approximately 1.5m wide), dug in the site's dominant vegetation type where fine root biomass sampling will also occur during Operations. To sample fine root biomass in each pit, soil samples of a known volume are taken from three vertical profiles down the face of the pit. Samples are then wet sieved to extract fine root mass, and roots are dried at 65°C for 48 hours and then weighed. The soil pit data are used to estimate the proportion of total fine root biomass from each site as a function of depth. Non-linear curves are fitted to the data to calculate total fine root mass at depth and to provide estimates of the proportion of the total fine root mass that is sampled at each site during NEON's 30 year operational sampling. The belowground

  19. A general review of competition genetic effects with an emphasis on swine breeding

    Science.gov (United States)

    A review of previous studies will be presented on estimates of genetic parameters and less than expected responses to selection with traditional breeding approaches, on correlations between competitive behavior and growth performance, on theoretical frameworks for selection incorporating competition...

  20. Strategizing for Intense Competition.

    Science.gov (United States)

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

    1999-01-01

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

  1. 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

  2. DEREGULATION, LIBERALIZATION AND CONSOLIDATION OF THE MEXICAN BANKING SYSTEM: EFFECTS ON COMPETITION

    OpenAIRE

    Liliana Solís; Joaquín Maudos Villarroya

    2007-01-01

    This paper analyses the evolution of competition in the Mexican banking system in the period 1993-2005, a period of deregulation, liberalization and consolidation of the sector. For this purpose we use two indicators of competition from the theory of industrial organization (the Lerner index and the Panzar and Rosse´s H-statistic). The empirical evidence does not permit us to reject the existence of monopolistic competition. The Lerner index shows a decrease in competitive rivalry in the depo...

  3. The Effects of Enhancing Competitiveness on FDI Inflows in CEE Countries

    OpenAIRE

    Oana Cristina POPOVICI; Adrian Cantemir CĂLIN

    2015-01-01

    The objective of this paper is to identify how an increase in competitiveness could improve FDI in ten Central and Eastern European (CEE) countries. For assessing competitiveness, we employ the variables used by World Economic Forum in designing the Global Competitiveness Index and find that half of the analyzed countries could see the most important increases in FDI/capita if making institutions more competitive, four other countries should accelerate on improving innovation and infrastructu...

  4. 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.

  5. The price effects of enhancing services sector competition in a large open economy

    NARCIS (Netherlands)

    P.A.D. Cavelaars

    2003-01-01

    textabstractThis paper studies the price e?ects of shocks to the degree of competition. It is motivated by initiatives to enhance competition in services in the European Union. The paper shows that a higher degree of competition in the nontradable goods sector may have adverse implications for inter

  6. 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...

  7. Microfinance in Times of Crisis: The Effects of Competition, Rising Indebtedness, and Economic Crisis on Repayment Behavior

    OpenAIRE

    Ulrike Vogelgesang

    2001-01-01

    This paper analyzes repayment determinants for loans from Caja Los Andes, a Bolivian microlender. The analysis focuses on the influence of recent changes in the Bolivian microfinance market. In particular, we examine the effects of the rapidly growing supply of funds for micro-loans, the increasing competition, a rising level of indebtedness among micro-entrepreneurs, and the recent economic crisis. Our results show a two-fold influence structure of competition and indebtedness. Firstly, clie...

  8. 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.

  9. Effect of a Karate Competition on Urinary Excretion of Proteins with High Molecular Weight (Glomerular proteinuria in Young Male Karatekas

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Kohanpour

    Full Text Available The aim of the present study was to investigate the effect of a karate competition on the urinary excretion of proteins with high molecular weight and urinary creatinine to protein ratio in young male karate as. Ten young male karate as with the age range of 25±2.63 years, height of 175.7±5.15 cm and weight of 71.5±8.61 kg voluntarily took part in this study and participated in a karate competition. Before and 20 min after the competition, the urinary sample was collected and the levels of albumin, total protein, creatinine and urinary creatinine to protein ratio were measured and calculated. To investigate the changes of urinary proteins caused by competition, the student’s t-test for dependent groups was used. Glomerular proteinuria increased after the competition; however, it was only significant for albumin and creatinine (p = 0.009 and p = 0.018, respectively. Although total protein increased after the competition, it was not statistically significant (p = 0.184 and the creatinine to protein ratio did not make any significant changes (p = 0.532. Creatinine to protein ratio was less than 0.1 for the samples before and after the competition; therefore, proteinuria had a physiological range which was very far from nephritic and pathological proteinuria ranges; thus, it was not harmful.

  10. 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

  11. The effect of substrate competition on the metabolism of polyphosphate accumulating organisms (PAOs).

    Science.gov (United States)

    Carvalheira, Mónica; Oehmen, Adrian; Carvalho, Gilda; Reis, Maria A M

    2014-11-01

    The type of carbon source present in the wastewater is one factor that affects the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) and therefore, the efficiency of the enhanced biological phosphorus removal (EBPR) process. This study investigated the impact of the carbon source composition on the anaerobic and aerobic kinetics of PAOs and the EBPR performance of an 85% PAO enrichment. When both acetate (HAc) and propionate (HPr) were present, propionate was depleted more quickly, with a constant uptake rate of 0.18 ± 0.02 C-mol/(C-mol biomass·h), while the acetate uptake rate decreased with an increase in propionate concentration, due to the substrate competition between acetate and propionate. The metabolic model for PAOs was modified to incorporate the anaerobic substrate competition effect. The aerobic rates for phosphorus (P) uptake, glycogen production and polyhydroxyalkanoates (PHA) degradation were within the same range for all tests, indicating that these rates are essentially independent of the acetate and propionate concentration, simplifying the calibration procedure for metabolic models. The metabolic model applied to describe the anaerobic and aerobic activity agreed well with the experimental data of HAc, HPr, P, PHA and biomass growth. The low glycogen consumption observed suggest that some reducing equivalents were generated anaerobically through the TCA cycle. The results of this work suggest that the propionate uptake kinetics by PAOs can provide them an advantage over GAOs in EBPR systems, even when the propionate fraction of the influent is relatively low. PMID:25051162

  12. Effects of mixing on drinking and competitive behavior of dairy calves.

    Science.gov (United States)

    O'Driscoll, K; von Keyserlingk, M A G; Weary, D M

    2006-01-01

    Group housing provides increased access to space and social interactions for calves while reducing labor costs for producers. However, group housing necessarily requires that calves be mixed and no research to date has addressed the effects of mixing on behavior of milk-fed dairy calves. The objective of this study was to monitor the feeding and competitive behavior of individual dairy calves (n = 8) after introduction into an established group of older calves fed ad libitum by a computer-controlled milk feeder. Milk feeding was monitored for 2 d before introduction into the new group and both milk feeding and competitive behaviors were monitored for 4 d after mixing. Mean (+/- SE) milk consumption before mixing was 9.7 +/- 0.7 kg/d, dropped slightly on the day of mixing to 8.6 +/- 0.6 kg/d, but increased on d 1 to 3 after mixing to 11.1 +/- 0.3 kg/d. Calves visited the feeder less frequently on the day of mixing (6.0 +/- 1.8 visits/d) than on either the days before mixing (20.3 +/- 2.5 visits/d) or the days after mixing (25.3 +/- 6.9 visits/ d). The mean duration of feeder visits and mean milk consumption per visit increased from 4 min 15 s +/- 21 s and 0.53 +/- 0.06 kg per visit before mixing to 8 min 17 s +/- 1 min 28 s and 1.87 +/- 0.51 kg per visit on the day of mixing. Competitive displacements from the milk-feeding stall were rare. In summary, feeding behavior of young calves is altered on the day of mixing, but calves are able to maintain milk intake when using a milk feeder fitted with a stall that prevents calves from displacing one another.

  13. Simulation and Visualisation of Functional Landscapes: Effects of the Water Resource Competition Between Plants

    Institute of Scientific and Technical Information of China (English)

    Vincent Le Chevalier; Marc Jaeger; Xing Mei; Paul-Henry Cournède

    2007-01-01

    Vegetation ecosystem simulation and visualisation are challenging topics involving multidisciplinary aspects. In this paper, we present a new generic frame for the simulation of natural phenomena through manageable and interacting models. It focuses on the functional growth of large vegetal ecosystems, showing coherence for scales ranging from the individual plant to communities and with a particular attention to the effects of water resource competition between plants. The proposed approach is based on a model of plant growth in interaction with the environmental conditions. These are deduced from the climatic data (light, temperature, rainfall) and a model of soil hydrological budget. A set of layers is used to store the water resources and to build the interfaces between the environmental data and landscape components: temperature, rain, light, altitude, lakes, plant positions, biomass, cycles, etc. At the plant level, the simulation is performed for each individual by a structural-functional growth model, interacting with the plant's environment. Temperature is spatialised, changing according to altitude, and thus locally controls plant growth speed. The competition for water is based on a soil hydrological model taking into account rainfalls, water runoff, absorption, diffusion, percolation in soil. So far, the incoming light radiation is not studied in detail and is supposed constant. However, competition for light between plants is directly taken into account in the plant growth model. In our implementation, we propose a simple architecture for such a simulator and a simulation scheme to synchronise the water resource updating (on a temporal basis) and the plant growth cycles (determined by the sum of daily temperatures). The visualisation techniques are based on sets of layers, allowing both morphological and functional landscape views and providing interesting tools for ecosystem management. The implementation of the proposed frame leads to encouraging

  14. Modelling the effects of plant facilitation-competition mechanisms on semiarid landscape co-evolution

    Science.gov (United States)

    Saco, Patricia M.

    2015-04-01

    Semiarid landscapes function as tightly coupled systems with strong biogeomorphic feedbacks. Worldwide, a vast portion of these areas are covered by patchy vegetation consisting of mixed herbaceous and woody plant species that interact exhibiting both competition and facilitation effects. Though the role of facilitative interactions in plant communities has received considerable attention in the last two decades, their effects on the coevolution of landscapes are still not clearly understood. Here a modelling framework is used to investigate the effects of facilitative interactions among vegetation species, as well as their role on the coevolution of water redistribution, vegetation patterns, and landforms. The model simulates the dynamics of and interactions between coexisting grasses and shrubs under varying competition-facilitation conditions. We explore facilitation effects associated with changes in micro environmental conditions for water availability in dry environments focussing on the role of infiltration enhancement and shading effects. Field experiments have shown that in many semiarid environments vegetation enhances infiltration. However, herbaceous and woody plants seem to have varying hydrologic traits in different areas and it is therefore not clear which species has the greatest contribution to infiltration enhancement. This study tests alternative hypothesis, varying the relative contributions to total infiltration of both species, through a sensitivity analysis of the key parameters affecting infiltration. We analyze the results by examining the simulated spatial patterns of biomass density, soil moisture and erosion. Results indicate that final vegetation cover structure and hydrologic connectivity strongly depend on the facilitation mechanisms included in the model. We find that the removal of woody species can lead to alternative steady states, including an increase on herbaceous cover, which is the expected outcome of these management

  15. The Effects of Enhancing Competitiveness on FDI Inflows in CEE Countries

    Directory of Open Access Journals (Sweden)

    Oana-Cristina POPOVICI

    2015-06-01

    Full Text Available The objective of this paper is to identify how an increase in competitiveness could improve FDI in ten Central and Eastern European (CEE countries. For assessing competitiveness, we employ the variables used by World Economic Forum in designing the Global Competitiveness Index and find that half of the analyzed countries could see the most important increases in FDI/capita if making institutions more competitive, four other countries should accelerate on improving innovation and infrastructure while another country should work on labour market efficiency. We also calculate the potential increase in FDI/capita due to similar changes in different competitiveness variables.

  16. 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

  17. 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

  18. 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

  19. Is the pro-competition policy an effective solution for China's public hospital reform?

    Science.gov (United States)

    Pan, Jay; Qin, Xuezheng; Hsieh, Chee-Ruey

    2016-10-01

    The new round of health care reforms in China achieved significant initial results. New and emerging problems coinciding with the deepening of the reforms, however, require further institutional changes to strengthen the competition mechanism and promote public hospital efficiency. This paper provides a conceptual framework and preliminary assessment of public hospital competition in China. Specifically, we distinguish between two closely related concepts - competition and privatization, and identify several critical conditions under which hospital competition can be used as a policy instrument to improve health care delivery in China. We also investigate the current performance and identify several unintended consequences of public hospital competition - mainly, medical arms race, drug over-prescription and the erosion of a trusting relationship between patients and physicians. Finally, we discuss the policy options for enhancing the internal competition in China's hospital market, and conclude that public investment on information provision is key to reaping the positive outcomes of pro-competition policies.

  20. 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....

  1. 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

    Intercropping advantages may be influenced by both plant density and relative frequency of the intercrop components. In a field study barley (Hordeum vulgare L.) and pea (Pisum sativum L.) were sole cropped and intercropped at three densities and with two relative frequencies when intercropped....... 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...... not increase its reliance on atmospheric nitrogen fixation compared to the pea sole crop. With respect to soil nitrogen uptake there were no effect of plant density but a strong effect of the relative frequency of pea in the intercrop, the greater the proportion the lower the uptake. Changes in the competitive...

  2. Effects of within-colony competition on body size asymmetries and reproductive skew in a social spider

    DEFF Research Database (Denmark)

    Grinsted, Lena; Bilde, Trine

    2013-01-01

    theoretical models suggest that reproductive skew is a result of contest competition within colonies, leading to size hierarchies where only the largest females become reproducers. We investigated the effect of competition on within-group body size variation over six months in S. dumicola, by manipulating...... food level and colony size. We found no evidence that competition leads to increased size asymmetry within colonies, suggesting that contest competition may not be the proximate explanation for reproductive skew. Within-colony body size variation was high already in the juvenile stage, and did...... not increase over the course of the experiment, suggesting that body size variation is shaped at an early stage. This might facilitate task specialization within colonies and ensure colony-level reproductive output by early allocation of reproductive roles. We suggest that reproductive skew in social spiders...

  3. Quantifying below-ground nitrogen of legumes: Optimizing procedures for 15N shoot-labelling

    International Nuclear Information System (INIS)

    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 15N-labelling of whole plants with subsequent measurement of 15N 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 15N labelling of four pulses, faba bean (Vicia faba), chickpea (Cicer arietinum), mung bean (Vigna radiata) and pigeon pea (Cajanus cajan). Treatments included 15N-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% 15N excess). The implications of uneven enrichment of the nodulated roots because of effects of the 15N-depleted nodules when calculating root-derived N in soil are discussed. (author)

  4. Effect of Gamma Irradiation And Some Plant Oils on Mating Competitiveness of Phthorimaea operculella (Zeller)(Lepidoptera: Gelechiidae)

    International Nuclear Information System (INIS)

    This study was carried out to investigate the effect of gamma radiation and plant oils on mating competitiveness of Phthorimaea operculella. When full grown pupae were irradiated with two sub-sterilizing doses and sterilizing dose (650 Gy) separately or combined with LC50 of 2% conc. Menth pepirita or Pelargonium graveolens. The fecundity and fertility were decreased by increasing the radiation dose. When males of Ph. operculella (Zeller) were sub-sterilized with gamma irradiation (150 or 200 Gy) or sterilized by 650 Gy and caged with non-irradiated pairs of adults at ratios of 1:1:1 and 5:1:1 (I male : U male : U female), the calculated degree of competitiveness showed that males irradiated with the lowest dose (150 Gy and 150 Gy + 2% conc. of M. pepirita or P. graveolens) were more competitive than males irradiated with the highest dose (650Gy). However, increasing the ratio of irradiated males with 650 Gy + 2% conc. M. pepirita to 10 increased the competitiveness value (CV), and the irradiated males were full competitive. The CV was more high among the irradiated males with 200 Gy while males were full competitive when irradiated and treated with 200 Gy + 2% conc. P. graveolens. The irradiated males with 150 Gy separately or combined with plant oil could be used in an effective sterile male release program at the ratio 1:1 (I male:N male) after suppression the field population with LC50 2% of plant oils M. pepirita or P. graveolens

  5. Effects of decabromodiphenyl ether (BDE-209 on inter-specific competition between two species of marine bloom-forming microalgae.

    Directory of Open Access Journals (Sweden)

    Xinxin Zhang

    Full Text Available Decabromodiphenyl ether (BDE-209, a new kind of persistent organic pollutants, was selected to investigate its influence on population growth and inter-specific competition between two species of marine bloom-forming microalgae, Heterosigma akashiwo and Karenia mikimotoi. (1BDE-209 showed acute toxic effects on both microalgae and H. akashiwo was more sensitive from view of 96 h-EC50 and the ultrastructure variation. (2The microalgal population growth patterns in mono-culture were density-dependent and the growth of both species in the normal co-culture was significantly depressed by competition (P<0.05 with different initial biomass ratios. BDE-209 exposure significantly changed the growth. (3 Lotka-Volterra competition model was used to simulate the interaction between the microalgae. BDE-209 exposure broke the competitive balance to make competition gradually shift in favor of H. akashiwo. Results suggested BDE-209 did have toxic effects on either microalgal growth or the inter-specific competition, which was quite different from previous reports. Further exploration of the mechanism is needed.

  6. INTRACEREBROVENTRICULAR APPLICATION OF COMPETITIVE AND NONCOMPETITIVE NMDA ANTAGONISTS INDUCE SIMILAR EFFECTS UPON RAT HIPPOCAMPAL ELECTROENCEPHALOGRAM AND LOCAL CEREBRAL GLUCOSE-UTILIZATION

    NARCIS (Netherlands)

    BODDEKE, HWGM; WIEDERHOLD, KH; PALACIOS, JM

    1992-01-01

    In this study we have used electrophysiological and metabolic markers to investigate the effects of competitive and non-competitive NMDA antagonists in rats after central or peripheral administration. The non-competitive antagonist, MK-801, induced dose-dependent suppression of rat hippocampal EEG e

  7. Modelling of Cs sorption in natural mixed-clays and the effects of ion competition

    International Nuclear Information System (INIS)

    Highlights: • Cs adsorption on natural clayrocks in saline marsh waters was studied. • Competitive ions effects on Cs sorption must be evaluated and quantified. • A model for Cs sorption accounting for rock and water chemistry was used. • The principal contribution to Cs sorption is given by the mineral illite. - Abstract: Cs migration in the environment is mainly controlled by sorption onto mineral surfaces, in particular on clay minerals. With the objective of designing a geochemical reactive barrier to treat 137Cs accidental pollution in an industrial waste repository, different natural clayrocks were studied to analyse their capacity to retain Cs. The simple semi-empiric Kd-approach for experimental data analysis, is unsatisfactory to describe the variability of sorption upon chemical changes. Indeed, due to the high salinity of the site, the effects of competitive ions must be evaluated and quantified. Thus, the development of sorption models, capable of reproducing experimental data obtained under conditions representative of the contaminated site, and applicable to reactive transport studies, is needed. In this study, a model for Cs sorption, which takes into account the main mineralogy of the sorbent, the composition of the natural water (and ion competition) was successfully applied to interpret the non-linear Cs sorption under natural conditions. The selectivity coefficients of Cs with respect to the most important cations present in the site water (Na, K, NH4, Ca) were derived by means of experiments in single clay minerals and synthetic mono-component solutions. Then, these parameters were tested in systems of increasing complexity. Considering the mineralogical composition of raw materials, it was shown that the principal contribution to Cs sorption is given by the mineral illite, while smectite starts to be relevant only at very high Cs loadings. Kaolinite, even in concentrations around 10 wt% of the clayey fraction, played only a minor role

  8. Fitness costs of chemical defense in Plantago lanceolata L.: effects of nutrient and competition stress.

    Science.gov (United States)

    Marak, Hamida B; Biere, Arjen; Van Damme, Jos M M

    2003-11-01

    Fitness costs of defense are often invoked to explain the maintenance of genetic variation in levels of chemical defense compounds in natural plant populations. We investigated fitness costs of iridoid glycosides (IGs), terpenoid compounds that strongly deter generalist insect herbivores, in ribwort plantain (Plantago lanceolata L.) using lines that had been artificially selected for high and low leaf IG concentrations for four generations. Twelve maternal half-sib families from each selection line were grown in four environments, consisting of two nutrient and two competition treatments. We tested whether: (1) in the absence of herbivores and pathogens, plants from lines selected for high IG levels have a lower fitness than plants selected for low IG levels; and (2) costs of chemical defense increase with environmental stress. Vegetative biomass did not differ between selection lines, but plants selected for high IG levels produced fewer inflorescences and had a significantly lower reproductive dry weight than plants selected for low IG levels, indicating a fitness cost of IG production. Line-by-nutrient and line-by-competition interactions were not significant for any of the fitness-related traits. Hence, there was no evidence that fitness costs increased with environmental stress. Two factors may have contributed to the absence of higher costs under environmental stress. First, IGs are carbon-based chemicals. Under nutrient limitation, the relative carbon excess may result in the production of IGs without imposing a further constraint on growth and reproduction. Second, correlated responses to selection on IG levels indicate the existence of a positive genetic association between IG level and cotyledon size. At low nutrient level, a path analysis based on family means revealed that in the presence of competitors, the negative direct effect of a high IG level on aboveground plant dry weight was partly offset by a positive direct effect of the associated larger

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

    International Nuclear Information System (INIS)

    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

  10. Effect of interspecific competition on trait variation in Phaeobacter inhibens biofilms.

    Science.gov (United States)

    Lutz, Carla; Thomas, Torsten; Steinberg, Peter; Kjelleberg, Staffan; Egan, Suhelen

    2016-05-01

    Interspecific competition between bacteria shapes community dynamics, causing evolutionary changes that affect life history traits. Here, we studied the role of interspecific competition on the generation of trait diversity using a two-species model system of marine, surface-associated bacteria. Bacterial biofilms of Phaeobacter inhibens were established alone or in competition with Pseudoalteromonas tunicata and phenotypic traits of dispersal cells were assessed during biofilm development. P. inhibens dispersal isolates from competition biofilms displayed less phenotypic variation, were superior competitors, were less susceptible to predation, and reached higher planktonic biomass than isolates from noncompetition biofilms. Moreover, the maintenance of competitive ability exhibited by individual dispersal isolates from competition biofilms did not result in an obvious reduction (measured as a negative trait correlation) in other traits, but was rather positively correlated with planktonic growth. However, where negative correlations between traits were found, they were exhibited by individuals derived from noncompetitive biofilms, whose populations also had a higher degree of trait variation than those from biofilms experiencing competition. Our observations indicate that interspecific competition during biofilm formation is important for maintaining both competitive ability and affects variation in ecologically relevant traits. Given that most bacteria in biofilms exist in diverse, multispecies communities, an understanding of how bacteria respond to biotic factors such as interspecific competition is critical for understanding the dynamics of bacterial populations in both ecological and evolutionary time.

  11. Effect of interspecific competition on trait variation in Phaeobacter inhibens biofilms.

    Science.gov (United States)

    Lutz, Carla; Thomas, Torsten; Steinberg, Peter; Kjelleberg, Staffan; Egan, Suhelen

    2016-05-01

    Interspecific competition between bacteria shapes community dynamics, causing evolutionary changes that affect life history traits. Here, we studied the role of interspecific competition on the generation of trait diversity using a two-species model system of marine, surface-associated bacteria. Bacterial biofilms of Phaeobacter inhibens were established alone or in competition with Pseudoalteromonas tunicata and phenotypic traits of dispersal cells were assessed during biofilm development. P. inhibens dispersal isolates from competition biofilms displayed less phenotypic variation, were superior competitors, were less susceptible to predation, and reached higher planktonic biomass than isolates from noncompetition biofilms. Moreover, the maintenance of competitive ability exhibited by individual dispersal isolates from competition biofilms did not result in an obvious reduction (measured as a negative trait correlation) in other traits, but was rather positively correlated with planktonic growth. However, where negative correlations between traits were found, they were exhibited by individuals derived from noncompetitive biofilms, whose populations also had a higher degree of trait variation than those from biofilms experiencing competition. Our observations indicate that interspecific competition during biofilm formation is important for maintaining both competitive ability and affects variation in ecologically relevant traits. Given that most bacteria in biofilms exist in diverse, multispecies communities, an understanding of how bacteria respond to biotic factors such as interspecific competition is critical for understanding the dynamics of bacterial populations in both ecological and evolutionary time. PMID:26914307

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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. PMID:26781048

  17. 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.

  18. Plant species distribution along environmental gradient: do belowground interactions with fungi matter?

    Directory of Open Access Journals (Sweden)

    Loïc ePellissier

    2013-12-01

    Full Text Available The distribution of plants along environmental gradients is constrained by abiotic and biotic factors. Cumulative evidence attests of the impact of abiotic factors on plant distributions, but only few studies discuss the role of belowground communities. Soil fungi, in particular, are thought to play an important role in how plant species assemble locally into communities. We first review existing evidence, and then test the effect of the number of soil fungal operational taxonomic units (OTUs on plant species distributions using a recently collected dataset of plant and metagenomic information on soil fungi in the Western Swiss Alps. Using species distribution models, we investigated whether the distribution of individual plant species is correlated to the number of OTUs of two important soil fungal classes known to interact with plants: the Glomeromycetes, that are obligatory symbionts of plants, and the Agaricomycetes, that may be facultative plant symbionts, pathogens, or wood decayers. We show that including the fungal richness information in the models of plant species distributions improves predictive accuracy. Number of fungal OTUs is especially correlated to the distribution of high elevation plant species. We suggest that high elevation soil show greater variation in fungal assemblages that may in turn impact plant turnover among communities. We finally discuss how to move beyond correlative analyses, through the design of field experiments manipulating plant and fungal communities along environmental gradients.

  19. Interactive effects of competition and predator cues on immune responses of leopard frogs at metamorphosis.

    Science.gov (United States)

    Groner, Maya L; Rollins-Smith, Louise A; Reinert, Laura K; Hempel, John; Bier, Mark E; Relyea, Rick A

    2014-02-01

    Recent hypotheses suggest that immunosuppression, resulting from altered environmental conditions, may contribute to the increased incidence of amphibian disease around the world. Antimicrobial peptides (AMPs) in amphibian skin are an important innate immune defense against fungal, viral and bacterial pathogens. Their release is tightly coupled with release of the stress hormone noradrenaline (norepinephrine). During metamorphosis, AMPs may constitute the primary immune response in the skin of some species because acquired immune functions are temporarily suppressed in order to prevent autoimmunity against new adult antigens. Suppression of AMPs during this transitional stage may impact disease rates. We exposed leopard frog tadpoles (Lithobates pipiens) to a factorial combination of competitor and caged-predator environments and measured their development, growth and production of hydrophobic skin peptides after metamorphosis. In the absence of predator cues, or if the exposure to predator cues was late in ontogeny, competition caused more than a 250% increase in mass-standardized hydrophobic skin peptides. Predator cues caused a decrease in mass-standardized hydrophobic skin peptides when the exposure was late in ontogeny under low competition, but otherwise had no effect. Liquid chromatography tandem mass spectrometry of the skin peptides showed that they include six AMPs in the brevinin and temporin families and at least three of these peptides are previously uncharacterized. Both of these peptide families have previously been shown to inhibit harmful microbes including Batrachochytrium dendrobatidis, the fungal pathogen associated with global amphibian declines. Our study shows that amphibians may be able to adjust their skin peptide defenses in response to stressors that are experienced early in ontogeny and that these effects extend through an important life-history transition.

  20. Interactive effects of competition and predator cues on immune responses of leopard frogs at metamorphosis.

    Science.gov (United States)

    Groner, Maya L; Rollins-Smith, Louise A; Reinert, Laura K; Hempel, John; Bier, Mark E; Relyea, Rick A

    2014-02-01

    Recent hypotheses suggest that immunosuppression, resulting from altered environmental conditions, may contribute to the increased incidence of amphibian disease around the world. Antimicrobial peptides (AMPs) in amphibian skin are an important innate immune defense against fungal, viral and bacterial pathogens. Their release is tightly coupled with release of the stress hormone noradrenaline (norepinephrine). During metamorphosis, AMPs may constitute the primary immune response in the skin of some species because acquired immune functions are temporarily suppressed in order to prevent autoimmunity against new adult antigens. Suppression of AMPs during this transitional stage may impact disease rates. We exposed leopard frog tadpoles (Lithobates pipiens) to a factorial combination of competitor and caged-predator environments and measured their development, growth and production of hydrophobic skin peptides after metamorphosis. In the absence of predator cues, or if the exposure to predator cues was late in ontogeny, competition caused more than a 250% increase in mass-standardized hydrophobic skin peptides. Predator cues caused a decrease in mass-standardized hydrophobic skin peptides when the exposure was late in ontogeny under low competition, but otherwise had no effect. Liquid chromatography tandem mass spectrometry of the skin peptides showed that they include six AMPs in the brevinin and temporin families and at least three of these peptides are previously uncharacterized. Both of these peptide families have previously been shown to inhibit harmful microbes including Batrachochytrium dendrobatidis, the fungal pathogen associated with global amphibian declines. Our study shows that amphibians may be able to adjust their skin peptide defenses in response to stressors that are experienced early in ontogeny and that these effects extend through an important life-history transition. PMID:24115058

  1. 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 st...

  2. Are NBA Policies that Promote Long-Term Competitive Balance Effective? What is the Price?

    OpenAIRE

    Corral Cuervo, Julio Florentino del; García Unanue, Jorge Fernando; Herencia Quintanar, Fernando

    2016-01-01

    This paper examines competitive balance in the most prominent basketball league in the world: the NBA. Two types of graphs are used. First, long-term competitive balance is studied based on actual positions achieved by the teams on the Regu-lar Season. On the other hand, the competitive balance levels for each season are analyzed using sport betting odds data and through the use of two alternative strategies. In the first approach, density functions for the number of victories for al...

  3. Alignment effects in beer mugs: Automatic action activation or response competition?

    Science.gov (United States)

    Roest, Sander A; Pecher, Diane; Naeije, Lilian; Zeelenberg, René

    2016-08-01

    Responses to objects with a graspable handle are faster when the response hand and handle orientation are aligned (e.g., a key press with the right hand is required and the object handle is oriented to the right) than when they are not aligned. This effect could be explained by automatic activation of specific motor programs when an object is viewed. Alternatively, the effect could be explained by competition at the response level. Participants performed a reach-and-grasp or reach-and-button-press action with their left or right hand in response to the color of a beer mug. The alignment effect did not vary as a function of the type of action. In addition, the alignment effect disappeared in a go/no-go version of the task. The same results were obtained when participants made upright/inverted decisions, so that object shape was task-relevant. Our results indicate that alignment effects are not due to automatic motor activation of the left or right limb.

  4. Relative effectiveness of mating success and sperm competition at eliminating deleterious mutations in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Sean C A Clark

    Full Text Available Condition-dependence theory predicts that sexual selection will facilitate adaptation by selecting against deleterious mutations that affect the expression of sexually selected traits indirectly via condition. Recent empirical studies have provided support for this prediction; however, their results do not elucidate the relative effects of pre- and postcopulatory sexual selection on deleterious mutations. We used the Drosophila melanogaster model system to discern the relative contributions of pre- and postcopulatory processes to selection against deleterious mutations. To assess second-male ejaculate competition success (P2; measured as the proportion of offspring attributable to the experimental male and mating success, mutant and wild-type male D. melanogaster were given the opportunity to mate with females that were previously mated to a standard competitor male. This process was repeated for males subjected to a diet quality manipulation to test for effects of environmentally-manipulated condition on P2 and mating success. While none of the tested mutations affected P2, there was a clear effect of condition. Conversely, several of the mutations affected mating success, while condition showed no effect. Our results suggest that precopulatory selection may be more effective than postcopulatory selection at removing deleterious mutations. The opposite result obtained for our diet manipulation points to an interesting discrepancy between environmental and genetic manipulations of condition, which may be explained by the multidimensionality of condition. Establishing whether the various stages of sexual selection affect deleterious mutations differently, and to what extent, remains an important issue to resolve.

  5. Alignment effects in beer mugs: Automatic action activation or response competition?

    Science.gov (United States)

    Roest, Sander A; Pecher, Diane; Naeije, Lilian; Zeelenberg, René

    2016-08-01

    Responses to objects with a graspable handle are faster when the response hand and handle orientation are aligned (e.g., a key press with the right hand is required and the object handle is oriented to the right) than when they are not aligned. This effect could be explained by automatic activation of specific motor programs when an object is viewed. Alternatively, the effect could be explained by competition at the response level. Participants performed a reach-and-grasp or reach-and-button-press action with their left or right hand in response to the color of a beer mug. The alignment effect did not vary as a function of the type of action. In addition, the alignment effect disappeared in a go/no-go version of the task. The same results were obtained when participants made upright/inverted decisions, so that object shape was task-relevant. Our results indicate that alignment effects are not due to automatic motor activation of the left or right limb. PMID:27184058

  6. 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)

  7. 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…

  8. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Science.gov (United States)

    Aragão, L. E. O. C.; Malhi, Y.; Metcalfe, D. B.; Silva-Espejo, J. E.; Jiménez, E.; Navarrete, D.; Almeida, S.; Costa, A. C. L.; Salinas, N.; Phillips, O. L.; Anderson, L. O.; Alvarez, E.; Baker, T. R.; Goncalvez, P. H.; Huamán-Ovalle, J.; Mamani-Solórzano, M.; Meir, P.; Monteagudo, A.; Patiño, S.; Peñuela, M. C.; Prieto, A.; Quesada, C. A.; Rozas-Dávila, A.; Rudas, A.; Silva, J. A., Jr.; Vásquez, R.

    2009-12-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha-1 yr-1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha-1 yr-1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha-1 yr-1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  9. 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. PMID:27197388

  10. 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.

  11. Increased effectiveness of competitive rhizobium strains upon inoculation of Cajanus cajan

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, B.S.; Poth, M.; Focht, D.D.

    1987-09-01

    A field study was conducted in lysimeters containing /sup 15/N-enriched soil to determine the effects of four competitive rhizobium strains upon yield parameters of pigeon peas (Cajanus cajan). The greatest differences observed were in seed yields; strain P132 effected the highest seed yield (121 +/- 20 g per plant), and the control strain (indigenous rhizobia) effected the lowest yield (43.9 +/- 8 g per plant). With the exception of seeds and pods, the dry matter weights were not different. Although there appeared to be no effect by inoculum strains on the fractional content of N derived from biological nitrogen fixation when the total plant biomass was considered, strains P132 and 401 partitioned more of the N derived from fixation into seeds and leaves than did the other strains. Because the seeds comprised the major portion of plant N, more total N and more N derived from biological nitrogen fixation (about half of total N) were found in plants inoculated with P132, whereas the smallest amount was found in the uninoculated controls. P132 was also the best competitor with respect to indigenous rhizobia and accounted for all of the nodules found on the plants in which it was inoculated.

  12. 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. PMID:24137146

  13. The effect of the competitive season in professional basketball on inflammation and iron metabolism.

    Science.gov (United States)

    Dzedzej, A; Ignatiuk, W; Jaworska, J; Grzywacz, T; Lipińska, P; Antosiewicz, J; Korek, A; Ziemann, E

    2016-09-01

    Following acute physical activity, blood hepcidin concentration appears to increase in response to exercise-induced inflammation, but the long-term impact of exercise on hepcidin remains unclear. Here we investigated changes in hepcidin and the inflammation marker interleukin-6 to evaluate professional basketball players' response to a season of training and games. The analysis also included vitamin D (25(OH)D3) assessment, owing to its anti-inflammatory effects. Blood samples were collected for 14 players and 10 control non-athletes prior to and after the 8-month competitive season. Athletes' performance was assessed with the NBA efficiency score. At the baseline hepcidin correlated with blood ferritin (r = 0.61; 90% CL ±0.31), but at the end of the season this correlation was absent. Compared with the control subjects, athletes experienced clear large increases in hepcidin (50%; 90% CI 15-96%) and interleukin-6 (77%; 90% CI 35-131%) and a clear small decrease in vitamin D (-12%; 90% CI -20 to -3%) at the season completion. Correlations between change scores of these variables were unclear (r = -0.21 to 0.24, 90% CL ±0.5), but their uncertainty generally excluded strong relationships. Athletes were hence concluded to have experienced acute inflammation at the beginning but chronic inflammation at the end of the competitive season. At the same time, the moderate correlation between changes in vitamin D and players' performance (r = 0.43) was suggestive of its beneficial influence. Maintaining the appropriative concentration of vitamin D is thus necessary for basketball players' performance and efficiency. The assessment of hepcidin has proven to be useful in diagnosing inflammation in response to chronic exercise. PMID:27601776

  14. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems

    Directory of Open Access Journals (Sweden)

    Joschka eBoedecker

    2013-10-01

    Full Text Available 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 prefrontal 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.

  15. The carry-over effect of competition in task-sharing: evidence from the joint Simon task.

    Directory of Open Access Journals (Sweden)

    Cristina Iani

    Full Text Available The Simon effect, that is the advantage of the spatial correspondence between stimulus and response locations when stimulus location is a task-irrelevant dimension, occurs even when the task is performed together by two participants, each performing a go/no-go task. Previous studies showed that this joint Simon effect, considered by some authors as a measure of self-other integration, does not emerge when during task performance co-actors are required to compete. The present study investigated whether and for how long competition experienced during joint performance of one task can affect performance in a following joint Simon task. In two experiments, we required pairs of participants to perform together a joint Simon task, before and after jointly performing together an unrelated non-spatial task (the Eriksen flanker task. In Experiment 1, participants always performed the joint Simon task under neutral instructions, before and after performing the joint flanker task in which they were explicitly required either to cooperate with (i.e., cooperative condition or to compete against a co-actor (i.e., competitive condition. In Experiment 2, they were required to compete during the joint flanker task and to cooperate during the subsequent joint Simon task. Competition experienced in one task affected the way the subsequent joint task was performed, as revealed by the lack of the joint Simon effect, even though, during the Simon task participants were not required to compete (Experiment 1. However, prior competition no longer affected subsequent performance if a new goal that created positive interdependence between the two agents was introduced (Experiment 2. These results suggest that the emergence of the joint Simon effect is significantly influenced by how the goals of the co-acting individuals are related, with the effect of competition extending beyond the specific competitive setting and affecting subsequent interactions.

  16. Studying the Effect of a Competitive Game Show in a Learning by Teaching Environment

    Science.gov (United States)

    Matsuda, Noboru; Yarzebinski, Evelyn; Keiser, Victoria; Raizada, Rohan; Stylianides, Gabriel J.; Koedinger, Kenneth R.

    2013-01-01

    In this paper we investigate how competition among tutees in the context of learning by teaching affects tutors' engagement as well as tutor learning. We conducted this investigation by incorporating a competitive Game Show feature into an online learning environment where students learn to solve algebraic equations by teaching a synthetic…

  17. Effectiveness of 14-15 years old tennis players’ competition functioning considering correction of their psychological fitness

    Directory of Open Access Journals (Sweden)

    Makuts T.B.

    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.

  18. 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.

  19. 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

  20. Competitive Intelligence.

    Science.gov (United States)

    Bergeron, Pierrette; Hiller, Christine A.

    2002-01-01

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

  1. Influences of competition level, gender, player nationality, career stage and playing position on relative age effects.

    Science.gov (United States)

    Schorer, J; Cobley, S; Büsch, D; Bräutigam, H; Baker, J

    2009-10-01

    Relative age, referring to the chronological age differences between individuals within annually age-grouped cohorts, is regarded as influential to an athlete's development, constraining athletic skill acquisition. While many studies have suggested different mechanisms for this effect, they have typically examined varying sports, precluding an examination of the possible inter-play between factors. Our three studies try to bridge this gap by investigating several moderators for relative age effects (RAEs) in one sport. Handball is a sport with position-specific demands, high cultural relevance and a performance context with established developmental structures and levels of representation for males and females. In Study 1, we investigated the influence of competition level and gender on RAEs before adulthood. In Study 2, elite participation, player nationality and stage of career are considered during adulthood. In Study 3, playing position and laterality (i.e., right vs left handedness) are investigated as moderators. Collectively, the results emphasize the complex inter-play of direct and indirect influences on RAEs in sports, providing evidence toward explaining how RAEs influence the development and maintenance of expertise.

  2. Effect of pedaling rate on submaximal exercise responses of competitive cyclists.

    Science.gov (United States)

    Hagberg, J M; Mullin, J P; Giese, M D; Spitznagel, E

    1981-08-01

    This investigation was undertaken to determine the effect of pedal frequency on submaximal exercise responses. Seven well-trained competitive cyclists were studied riding their road-racing bicycles on a motor-driven treadmill at 80% of maximum O2 consumption (VO2 max) using different gear ratios. Cyclists were also studied during a series of unloaded trials to assess the effects of varying rates of limb movements independent of external work load. Heart rate (HR) increased, whereas net HR (after subtracting the HR during unloaded cycling) decreased with increasing pedal frequency during loaded cycling. Expiratory flow (VE), O2 consumption (VO2), blood lactate, net VO2 (after subtracting the VO2 of unloaded cycling), and net VE (after subtracting the VE during unloaded cycling) were quadratically related to pedal frequency. The quadratic relationships evident after corrections were made for the additional work needed to move the legs more frequently may be explained at the lower pedaling rates by a less uniform pattern of blood flow caused by increasing the force requirement per pedal stroke and, at the higher pedal frequencies, by the recruitment of additional musculature to stabilize the trunk. The average of preferred frequency for the group, which was also the most economical pedaling rate judged by most of the variables was 91 rpm, although the preferred pedaling rate for each subject ranged from 72 to 102 rpm.

  3. 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

  4. Within-population genetic diversity of Taraxacum officinale (Asteraceae): differential genotype response and effect on interspecific competition.

    Science.gov (United States)

    Vavrek, M

    1998-07-01

    Clonal offspring of five morphologically distinct individuals of Taraxacum officinale were planted in a greenhouse experiment with each of three competitors, Plantago major, Poa pratensis and Trifolium pratense. The competitors were chosen to represent a series of competitive environments experienced by a natural population of T. officinale through the year. Differences in size, morphology, and response to the competitive environments were found among clones and support classification of the five individuals as distinct genotypes. Both differential competitive responses (alteration in performance) and competitive effects (impediment by competitor performance) were exhibited among genotypes. The differential response by the T. officinale genotypes to the competitors indicates that the biotic environment may influence the genetic structure of a population. The biotic environment in this case is determined by the sequential appearance and dominance of competitors in a field rather than the spatial distribution of these competitors. Since competitors change in relative dominance across seasons, competition is likely to be a component of the genotype by season interaction that had been observed in the natural population. Thus, differential responses among genotypes to a temporally and spatially fluctuating biotic environment may contribute to the maintenance of within-population genetic diversity. PMID:21684978

  5. Aboveground and belowground legacies of native Sami land use on boreal forest in northern Sweden 100 years after abandonment.

    Science.gov (United States)

    Freschet, Grégoire T; Ostlund, Lars; Kichenin, Emilie; Wardle, David A

    2014-04-01

    Human activities that involve land-use change often cause major transformations to community and ecosystem properties both aboveground and belowground, and when land use is abandoned, these modifications can persist for extended periods. However, the mechanisms responsible for rapid recovery vs. long-term maintenance of ecosystem changes following abandonment remain poorly understood. Here, we examined the long-term ecological effects of two remote former settlements, regularly visited for -300 years by reindeer-herding Sami and abandoned -100 years ago, within an old-growth boreal forest that is considered one of the most pristine regions in northern Scandinavia. These human legacies were assessed through measurements of abiotic and biotic soil properties and vegetation characteristics at the settlement sites and at varying distances from them. Low-intensity land use by Sami is characterized by the transfer of organic matter towards the settlements by humans and reindeer herds, compaction of soil through trampling, disappearance of understory vegetation, and selective cutting of pine trees for fuel and construction. As a consequence, we found a shift towards early successional plant species and a threefold increase in soil microbial activity and nutrient availability close to the settlements relative to away from them. These changes in soil fertility and vegetation contributed to 83% greater total vegetation productivity, 35% greater plant biomass, and 23% and 16% greater concentrations of foliar N and P nearer the settlements, leading to a greater quantity and quality of litter inputs. Because decomposer activity was also 40% greater towards the settlements, soil organic matter cycling and nutrient availability were further increased, leading to likely positive feedbacks between the aboveground and belowground components resulting from historic land use. Although not all of the activities typical of Sami have left visible residual traces on the ecosystem after

  6. 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

  7. Models of Experimentally Derived Competitive Effects Predict Biogeographical Differences in the Abundance of Invasive and Native Plant Species

    Science.gov (United States)

    Xiao, Sa; Ni, Guangyan; Callaway, Ragan M.

    2013-01-01

    Mono-dominance by invasive species provides opportunities to explore determinants of plant distributions and abundance; however, linking mechanistic results from small scale experiments to patterns in nature is difficult. We used experimentally derived competitive effects of an invader in North America, Acroptilon repens, on species with which it co-occurs in its native range of Uzbekistan and on species with which it occurs in its non-native ranges in North America, in individual-based models. We found that competitive effects yielded relative abundances of Acroptilon and other species in models that were qualitatively similar to those observed in the field in the two ranges. In its non-native range, Acroptilon can occur in nearly pure monocultures at local scales, whereas such nearly pure stands of Acroptilon appear to be much less common in its native range. Experimentally derived competitive effects of Acroptilon on other species predicted Acroptilon to be 4–9 times more proportionally abundant than natives in the North American models, but proportionally equal to or less than the abundance of natives in the Eurasian models. Our results suggest a novel way to integrate complex combinations of interactions simultaneously, and that biogeographical differences in the competitive effects of an invader correspond well with biogeographical differences in abundance and impact. PMID:24265701

  8. Models of experimentally derived competitive effects predict biogeographical differences in the abundance of invasive and native plant species.

    Directory of Open Access Journals (Sweden)

    Sa Xiao

    Full Text Available Mono-dominance by invasive species provides opportunities to explore determinants of plant distributions and abundance; however, linking mechanistic results from small scale experiments to patterns in nature is difficult. We used experimentally derived competitive effects of an invader in North America, Acroptilon repens, on species with which it co-occurs in its native range of Uzbekistan and on species with which it occurs in its non-native ranges in North America, in individual-based models. We found that competitive effects yielded relative abundances of Acroptilon and other species in models that were qualitatively similar to those observed in the field in the two ranges. In its non-native range, Acroptilon can occur in nearly pure monocultures at local scales, whereas such nearly pure stands of Acroptilon appear to be much less common in its native range. Experimentally derived competitive effects of Acroptilon on other species predicted Acroptilon to be 4-9 times more proportionally abundant than natives in the North American models, but proportionally equal to or less than the abundance of natives in the Eurasian models. Our results suggest a novel way to integrate complex combinations of interactions simultaneously, and that biogeographical differences in the competitive effects of an invader correspond well with biogeographical differences in abundance and impact.

  9. A PATH ANALYTICAL ANALYSIS OF ORGANIZATIONAL INTEGRATION PRACTICES' EFFECTS ON MANUFACTURING FLEXIBILITY AND COMPETITIVE ADVANTAGE

    Institute of Scientific and Technical Information of China (English)

    Mei CAO; Qingyu ZHANG

    2008-01-01

    To cope with an increasingly turbulent environment, manufacturing firms increasingly implement integration practices to enhance flexibility in the production process. This research develops a framework to explore the relationships among organizational integration practices, manufacturing flexibility, and competitive advantage. The study develops valid and reliable instruments to measure these constructs, and it applies structural equation modeling to test relationships among these variables using a large sample. The results indicate strong, positive, and direct relationships between organizational integration practices and manufacturing flexibility, and between manufacturing flexibility and competitive advantage. The results also indicate that organizational integration practices enhance competitive advantage directly as well as indirectly by facilitating manufacturing flexibility.

  10. The Effects of Tax Competition when Politicians Create Rents to Buy Political Support

    DEFF Research Database (Denmark)

    Eggert, Wolfgang; Sørensen, Peter Birch

    . 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...

  11. 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

    . 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...

  12. Do Species Mixtures Increase Above- and Belowground Resource Capture in Woody and Herbaceous Tropical Legumes?

    NARCIS (Netherlands)

    Gathumbi, S.M.; Ndufa, J.K.; Giller, K.E.; Cadisch, G.

    2002-01-01

    The rotation of crops with planted, N2-fixing legumes is a promising agroforestry innovation for replenishing soil fertility in the tropics. We postulated that woody and herbaceous legumes with different growth and rooting patterns could be mixed to optimize above- and belowground resource capture.

  13. 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 t

  14. 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 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...

  15. Hotel Competitiveness Measurement Methods

    OpenAIRE

    Katalin Juhasz-Dora

    2015-01-01

    Competitiveness is becoming a very common expression used in business administration. The definition and its application still raises some questions due to the complexity of its meaning. The role of the measurement of competitiveness and its effect on performance and profitability is increasing in the field of hospitality and tourism as well. The measurement of hotel competitiveness is a current issue in business life due to globalization, sharing economy and the change in the consumber habit...

  16. Additivity pretraining and cue competition effects: developmental evidence for a reasoning-based account of causal learning.

    Science.gov (United States)

    Simms, Victoria; McCormack, Teresa; Beckers, Tom

    2012-04-01

    The effect of additivity pretraining on blocking has been taken as evidence for a reasoning account of human and animal causal learning. If inferential reasoning underpins this effect, then developmental differences in the magnitude of this effect in children would be expected. Experiment 1 examined cue competition effects in children's (4- to 5-year-olds and 6- to 7-year-olds) causal learning using a new paradigm analogous to the food allergy task used in studies of human adult causal learning. Blocking was stronger in the older than the younger children, and additivity pretraining only affected blocking in the older group. Unovershadowing was not affected by age or by pretraining. In experiment 2, levels of blocking were found to be correlated with the ability to answer questions that required children to reason about additivity. Our results support an inferential reasoning explanation of cue competition effects.

  17. Relative age effect on success in tennis competition in the older age-school children

    OpenAIRE

    Adrián Agricola; Rudolf Psotta; Reza Abdollahipour

    2015-01-01

    BACKGROUND: The theory of relative age effect assumes that children and adolescents - athletes born at the beginning of the calendar year in sports competitions are more successful than those who were born in the later months of the same year. This percentage is based on advantage of fitness, morphological and psychological assumptions of the older athletes. AIM: The research objective of the present study was to verify the assumption of competitive success of older players in the elite...

  18. The effect of foreign competition on product switching activities: A firm level analysis

    OpenAIRE

    Nakhoda, Aadil

    2012-01-01

    Pressure from foreign competition on the decision to introduce new products or on production costs may influence firms to particpate in product switching activities. Firms switch products if they either add or drop products within their product range. I test whether pressure from foreign competition is likely to influence firms that concurrently add and drop (churn) products rather than firms that i) do not undertake any product switching activity, ii) add products only, or iii) drop products...

  19. Side Effects of Competition: the Role of Advertising and Promotion in Pharmaceutical Markets

    OpenAIRE

    Guy David; Sara Markowitz

    2011-01-01

    The extent of pharmaceutical advertising and promotion can be characterized by a balancing act between profitable demand expansions and potentially unfavorable subsequent regulatory actions. However, this balance also depends on the nature of competition (e.g. monopoly versus oligopoly). In this paper we model the firm's behavior under different competitive scenarios and test the model's predictions using a novel combination of sales, promotion, advertising, and adverse event reports data. We...

  20. EFFECT OF NEGATIVE EMOTIONAL RESPONSE TO COMPETITIVE STRESSORS ON SPORTS ACHIEVEMENTS OF BASKETBALL PLAYERS

    OpenAIRE

    Santosh Bajpai; Avinash Yadav

    2016-01-01

    The aim of the present study is to compare sports competitive anxiety between national, state and district level male basketball players. For present study, 100 national level male basketball players (Ave. age 25.12 yrs.), 100 state level male basketball players (Ave. age 22.34 yrs.) and 100 district level male basketball players (Ave. age 21.92 yrs.) were selected as sample. The sample was collected through convenience sampling method. Sports Competitive Anxiety Test (SCAT) constructed and s...

  1. Effects of competition on the sleep patterns of elite rugby union players.

    Science.gov (United States)

    Shearer, David A; Jones, Rhys M; Kilduff, Liam P; Cook, Christian J

    2015-01-01

    No published research has assessed sleep patterns of elite rugby union players following match-play. The present study examined sleep patterns of professional rugby union players, prior and post-match-play, to assess the influence of competition. Twenty-eight male rugby union players (24.4 ± 2.9 years, 103.9 ± 12.2 kg) competed in one of four competitive home matches. Player's sleep behaviours were monitored continuously using an Actiwatch® from two days before the match, until three days post-match. Repeated measures of analysis of variance (ANOVA) showed significant differences across the time points measured for time to bed (F = 26.425, η(2)  = 0.495, p < .001), get up time (F = 21.175, η(2) = 0.440, p < .001), time spent in bed (F = 10.669, η(2) = 0.283, p < .001), time asleep (F = 8.752, η(2) = 0.245, p < .001) and percentage of time moving (F = 4.602, η(2) = 0.146 p < .05). Most notable, post hocs revealed a significant increase for time in bed the night before the match (p < .01; 95% CI = 0 : 10-1 : 28 h; 9.7 ± 13.5%) compared with the reference night sleep. Furthermore, time asleep significantly decreased post-match (p < .05; 95% CI = -0:03 to -1:59 h; -19.5 ± 19.8%) compared to two nights pre-match. Across all time points, sleep latency and efficiency for most players were considered abnormal compared to that expected in normal populations. The results demonstrate that sleep that is deprived post-match may have detrimental effects on the recovery process.

  2. The Effects of Training on the Competitive Economic Advantage of Companies in Spain

    Directory of Open Access Journals (Sweden)

    Maria Luz Marin-Diaz

    2014-01-01

    Full Text Available The search for factors that lead to competitive advantage in a company in relation to its competitors is a widely debated subject; a wide range of issues have been examined to determine which factors are the most influential. The aim of this paper is to study training effect on business results (particularly on firm’s financial turnover. For the present research, the classical model of Industrial Economy as a frame of reference has been used. The data collection instrument was a questionnaire sent to 381 large organizations in Catalonia (Spain during 2009 and 2010. The empirical section of the present article was developed using structural equation modeling (SEM. Results relate training to company’s financial turnover in a positive way. The General Expenditure and Costs is the variable that most contributes to the explanation of firms’ financial turnover. The Organization of Training variable is the second most important construct to account for financial turnover However, training is required to be well organized as well as properly financed.

  3. 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.

  4. The Impact of Supply Chain Management Practices on Supply Chain Performance in Jordan: The Moderating Effect of Competitive Intensity

    OpenAIRE

    Ayman Bahjat Abdallah; Bader Yousef Obeidat; Noor Osama Aqqad

    2014-01-01

    The purpose of this study is to test the impact of supply chain management practices on supply chainperformance in terms of supply chain efficiency and supply chain effectiveness. Additionally, we investigate themoderating effect of competitive intensity on the relationship between supply chain management practices andsupply chain performance. Data for this research were collected from 104 manufacturing companies in Jordan.Hierarchical regressions were used to test the hypothesized relationsh...

  5. Annual clovers and medics in living mulch systems: Competition and effect on N supply and soil fertility

    OpenAIRE

    Reents, Dr. H. J.; Baresel, Dr. J. P.

    2008-01-01

    The potential of a large number of species of self-reseeding annual clovers and medics as continuous ground cover in living mulch systems with cereals in southern Germany and their effect on N supply and soil properties were assessed. Adapted legume species could be identified. The competition of the legumes on rye was limited but not on wheat. Positive effects on N supply and on indicators of soil fertility could be evidenced

  6. Belowground carbon trade among tall trees in a temperate forest.

    Science.gov (United States)

    Klein, Tamir; Siegwolf, Rolf T W; Körner, Christian

    2016-04-15

    Forest trees compete for light and soil resources, but photoassimilates, once produced in the foliage, are not considered to be exchanged between individuals. Applying stable carbon isotope labeling at the canopy scale, we show that carbon assimilated by 40-meter-tall spruce is traded over to neighboring beech, larch, and pine via overlapping root spheres. Isotope mixing signals indicate that the interspecific, bidirectional transfer, assisted by common ectomycorrhiza networks, accounted for 40% of the fine root carbon (about 280 kilograms per hectare per year tree-to-tree transfer). Although competition for resources is commonly considered as the dominant tree-to-tree interaction in forests, trees may interact in more complex ways, including substantial carbon exchange. PMID:27081070

  7. Belowground carbon trade among tall trees in a temperate forest.

    Science.gov (United States)

    Klein, Tamir; Siegwolf, Rolf T W; Körner, Christian

    2016-04-15

    Forest trees compete for light and soil resources, but photoassimilates, once produced in the foliage, are not considered to be exchanged between individuals. Applying stable carbon isotope labeling at the canopy scale, we show that carbon assimilated by 40-meter-tall spruce is traded over to neighboring beech, larch, and pine via overlapping root spheres. Isotope mixing signals indicate that the interspecific, bidirectional transfer, assisted by common ectomycorrhiza networks, accounted for 40% of the fine root carbon (about 280 kilograms per hectare per year tree-to-tree transfer). Although competition for resources is commonly considered as the dominant tree-to-tree interaction in forests, trees may interact in more complex ways, including substantial carbon exchange.

  8. External Costs and Benefits of Energy. Methodologies, Results and Effects on Renewable Energies Competitivity

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    Ehreth, J

    1993-01-01

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

  10. The Effect of TQM Practices on Corporate Performance and Competitive Advantage as Mediating Variable: Study at Manufacturing Companies in Makassar, South Sulawesi Province, Indonesia

    OpenAIRE

    Munizu, Musran

    2013-01-01

    This study conducts a comprehensive review of the literature and develops a framework that links among TQM practices, competitive advantage, and corporate performance. The paper provides empirical support for direct and indirect effects of TQM practices on competitive advantage and corporate performance. The purpose of this research is to empirically investigate the impact of TQM practices on competitive advantage and corporate performance.The study utilized primary data obtained from a quest...

  11. Interspecific competition effects on phosphorus accumulation by Hydrilla verticillata and Vallisneria natans

    Institute of Scientific and Technical Information of China (English)

    Xiufeng Zhang; Zhengwen Liu

    2011-01-01

    The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities in shallow lakes.The ability of different species to take up and store nutrients from the surrounding ambience varies,and hence plant community structure might be expected to affect the cycling of nutrients in lake ecosystems.In this study,the uptake of phosphorus by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings.Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by competition.However,the quantity of phosphorus accumulated by whole plants of H.verticillata was significantly higher in mixture culture than in monoculture,while that of V.natans was lower in the mixed culture.The results indicated that H.verticillata has a competitive advantage over V.natant,when the two species are grown in competition,and is able to accumulate a greater quantity of phosphorus.

  12. Ascertaining effects of nanoscale polymeric interfaces on competitive protein adsorption at the individual protein level.

    Science.gov (United States)

    Song, Sheng; Xie, Tian; Ravensbergen, Kristina; Hahm, Jong-in

    2016-02-14

    With the recent development of biomaterials and biodevices with reduced dimensionality, it is critical to comprehend protein adhesion processes to nanoscale solid surfaces, especially those occurring in a competitive adsorption environment. Complex sequences of adhesion events in competitive adsorption involving multicomponent protein systems have been extensively investigated, but our understanding is still limited primarily to macroscopic adhesion onto chemically simple surfaces. We examine the competitive adsorption behavior from a binary protein mixture containing bovine serum albumin and fibrinogen at the single protein level. We subsequently evaluate a series of adsorption and displacement processes occurring on both the macroscopic homopolymer and nanoscopic diblock copolymer surfaces, while systematically varying the protein concentration and incubation time. We identify the similarities and dissimilarities in competitive protein adsorption behavior between the two polymeric surfaces, the former presenting chemical uniformity at macroscale versus the latter exhibiting periodic nanointerfaces of chemically alternating polymeric segments. We then present our novel experimental finding of a large increase in the nanointerface-engaged residence time of the initially bound proteins and further explain the origin of this phenomenon manifested on nanoscale diblock copolymer surfaces. The outcomes of this study may provide timely insight into nanoscale competitive protein adsorption that is much needed in designing bioimplant and tissue engineering materials. In addition, the fundamental understanding gained from this study can be beneficial for the development of highly miniaturized biodevices and biomaterials fabricated by using nanoscale polymeric materials and interfaces. PMID:26794230

  13. Ascertaining effects of nanoscale polymeric interfaces on competitive protein adsorption at the individual protein level.

    Science.gov (United States)

    Song, Sheng; Xie, Tian; Ravensbergen, Kristina; Hahm, Jong-in

    2016-02-14

    With the recent development of biomaterials and biodevices with reduced dimensionality, it is critical to comprehend protein adhesion processes to nanoscale solid surfaces, especially those occurring in a competitive adsorption environment. Complex sequences of adhesion events in competitive adsorption involving multicomponent protein systems have been extensively investigated, but our understanding is still limited primarily to macroscopic adhesion onto chemically simple surfaces. We examine the competitive adsorption behavior from a binary protein mixture containing bovine serum albumin and fibrinogen at the single protein level. We subsequently evaluate a series of adsorption and displacement processes occurring on both the macroscopic homopolymer and nanoscopic diblock copolymer surfaces, while systematically varying the protein concentration and incubation time. We identify the similarities and dissimilarities in competitive protein adsorption behavior between the two polymeric surfaces, the former presenting chemical uniformity at macroscale versus the latter exhibiting periodic nanointerfaces of chemically alternating polymeric segments. We then present our novel experimental finding of a large increase in the nanointerface-engaged residence time of the initially bound proteins and further explain the origin of this phenomenon manifested on nanoscale diblock copolymer surfaces. The outcomes of this study may provide timely insight into nanoscale competitive protein adsorption that is much needed in designing bioimplant and tissue engineering materials. In addition, the fundamental understanding gained from this study can be beneficial for the development of highly miniaturized biodevices and biomaterials fabricated by using nanoscale polymeric materials and interfaces.

  14. 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. PMID:10564599

  15. The effect of nitrogen addition on biomass production and competition in three expansive tall grasses

    International Nuclear Information System (INIS)

    A large increase of grasses Calamagrostis epigejos, Bromus inermis and Brachypodium pinnatum has often been observed in many regions enriched by higher nitrogen (N) wet deposition inputs. Competitive relationships between these grasses under enhanced N loads have not yet been studied. Therefore an outdoor experiment was established which involved monocultures of Calamagrostis, Bromus and Brachypodium and their 1:1 mixtures in containers under two N treatments, i.e., unfertilized and fertilized (+50 kg N ha−1). In monocultures, the total aboveground biomass of Calamagrostis, Bromus and Brachypodium were 1.1, 3.6 and 2.5 times higher respectively due to enhanced N fertilization. Relative crowding and aggressivity coefficients indicate that Calamagrostis and Bromus dominate when mixed with Brachypodium at both levels of N availability. When mixed with Bromus, Calamagrostis is the poorer competitor at lower N loads, however, it can be dominating in N fertilized treatments. - Highlights: ► A large increase of tall grasses has often been observed in many ecosystems. ► Data on competitive relationships between grasses were investigated. ► Competition indices indicate that Calamagrostis and Bromus dominate in mixtures with Brachypodium. ► Calamagrostis is a better competitor when mixed with Bromus but only at higher N loads. ► N deposition may play a critical role in the expansion and persistence of grasses in the landscape. - Competition abilities of Calamagrostis and Bromus were greater than Brachypodium and the competitive superiority of Calamagrostis to Bromus was in N rich substrate.

  16. Interspecific competition effects on phosphorus accumulation by Hydrilla verticillata and Vallisneria natans.

    Science.gov (United States)

    Zhang, Xiufeng; Liu, Zhengwen

    2011-01-01

    The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities in shallow lakes. The ability of different species to take up and store nutrients from the surrounding ambience varies, and hence plant community structure might be expected to affect the cycling of nutrients in lake ecosystems. In this study, the uptake of phosphorus by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings. Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by competition. However, the quantity of phosphorus accumulated by whole plants of H. verticillata was significantly higher in mixture culture than in monoculture, while that of V. natans was lower in the mixed culture. The results indicated that H. verticillata has a competitive advantage over V. natans, when the two species are grown in competition, and is able to accumulate a greater quantity of phosphorus. PMID:22128533

  17. Decreased Empathic Responses to the 'Lucky Guy' in Love: The Effect of Intrasexual Competition.

    Science.gov (United States)

    Zheng, Li; Zhang, Fangxiao; Wei, Chunli; Xu, Jialin; Wang, Qianfeng; Zhu, Lei; Roberts, Ian D; Guo, Xiuyan

    2016-01-01

    People have a greater desire to date highly attractive partners, which induces intrasexual competition between same-sex individuals. The present study used functional magnetic resonance imaging to explore whether and how intrasexual competition modulates pain empathy for a same-sex rival and the underlying neural mechanism. Participants were scanned while processing the pain of a same-sex 'lucky guy' who had an attractive partner and one with a plain partner. The results revealed that participants reported lower pain intensity for the lucky guy. Neurally, reduced pain-related activations in anterior insula and anterior mid-cingulate cortex and increased activations in right superior frontal gyrus (SFG) and medial prefrontal gyrus (MPFC) were found for the lucky guy compared to the one with a plain partner. Right SFG and MPFC activations could predict participants' subsequent pain intensity ratings for the lucky guy. These findings suggest intrasexual competition can modulate normal empathic responses. PMID:27242579

  18. THE EFFECT OF SPORT COMPETITION ON SALIVARY STEROIDS IN AMATEUR FEMALE KARATE ATHLETES

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Azarbayjani

    2010-06-01

    Full Text Available The purpose of present study was to investigate the impact of repeated competition on salivary cortisol and DHEA-S in amateur women karate athletes. We recruited 20 young elite female karate fighters [height 158 ± 7 cm (mean ± S.D., weight 59.5 ± 10.9 kg, age 21.1 ± 3.0 years], who were placed first till fourth in the Iranian championship tournament. Five ml of unstimulated whole saliva was collected 30-min before and 5 - min after first and last match in competition and analyzed for cortisol and DHEA-S concentrations. The results showed that participation in competition resulted in significantly increased saliva cortisol level (p 0.05. Significant differences insalivary steroids were not different between winners and losers (p > 0.05. The results of present study show that salivary cortisol concentration is a suitable index for showing competing stress.

  19. Adsorption of divalent metals to metal oxide nanoparicles: Competitive and temperature effects

    Science.gov (United States)

    Grover, Valerie Ann

    The presence of metals in natural waters is becoming a critical environmental and public health concern. Emerging nanotechnology and the use of metal oxide nanoparticles has been identified as a potential remediation technique in removing metals from water. However, practical applications are still being explored to determine how to apply their unique chemical and physical properties for full scale remediation projects. This thesis investigates the sorption properties of Cd(II), Cu(II), Pb(II) and Zn(II) to hematite (alpha-Fe2O3) and titanium dioxide (TiO2) nanoparticles in single- and binary-adsorbate systems. Competitive sorption was evaluated in 1L batch binary-metal systems with 0.05g/L nano-hematite at pH 8.0 and pH 6.0. Results indicate that the presence of a secondary metal can affect the sorption process depending upon the molar ratios, such as increased or reduced adsorption. Thermodynamic properties were also studied in order to better understand the effects of temperature on equilibrium and kinetic adsorption capabilities. Understanding the thermodynamic properties can also give insight to determine if the sorption process is a physical, chemical or ion exchange reaction. Thermodynamic parameters such as enthalpy (DeltaH), entropy (DeltaS), and Gibbs free energy (DeltaG) were evaluated as a function of temperature, pH, and metal concentration. Results indicate that Pb(II) and Cu(II) adsorption to nano-hematite was an endothermic and physical adsorption process, while Zn(II) and Cd(II) adsorption was dependent upon the adsorbed concentration evaluated. However, metal adsorptions to nano-titanium dioxide were all found to be endothermic and physical adsorption processes; the spontaneity of metal adsorption was temperature dependent for both metal oxide nanoparticles.

  20. Effects of training at simulated altitude on performance and muscle metabolic capacity in competitive road cyclists.

    Science.gov (United States)

    Terrados, N; Melichna, J; Sylvén, C; Jansson, E; Kaijser, L

    1988-01-01

    Differences between the effects of training at sea level and at simulated altitude on performance and muscle structural and biochemical properties were investigated in 8 competitive cyclists who trained for 3-4 weeks, 4-5 sessions/week, each session consisting of cycling for 60-90 min continuously and 45-60 min intermittently. Four subjects, the altitude group (AG), trained in a hypobaric chamber (574 torr = 2300 m above sea level), and the other four at sea level (SLG). Before and after training work capacity was tested both at simulated altitude (574 torr) and at sea level, by an incremental cycle ergometer test until exhaustion. Work capacity was expressed as total amount of work performed. Venous blood samples were taken during the tests. Leg muscle biopsies were taken at rest before and after the training period. AG exhibited an increase of 33% in both sea level and altitude performance, while SLG increased 22% at sea level and 14% at altitude. Blood lactate concentration at a given submaximal load at altitude was significantly more reduced by training in AG than SLG. Muscle phosphofructokinase (PFK) activity decreased with training in AG but increased in SLG. All AG subjects showed increases in capillary density. In conclusion, work capacity at altitude was increased more by training at altitude than at sea level. Work capacity at sea level was at least as much improved by altitude as by sea level training. The improved work capacity by training at altitude was paralleled by decreased exercise blood lactate concentration, increased capillarization and decreased glycolytic capacity in leg muscle.

  1. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Directory of Open Access Journals (Sweden)

    L. E. O. C. Aragão

    2009-02-01

    Full Text Available The net primary productivity (NPP of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1 How do Amazonian forests allocate productivity among its above- and below-ground components? (2 How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha−1 yr−1 (mean±standard error, at a white sand plot, and 17.0±1.4 Mg C ha−1 yr−1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha−1 yr−1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  2. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Directory of Open Access Journals (Sweden)

    L. E. O. C. Aragão

    2009-12-01

    Full Text Available The net primary productivity (NPP of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1 How do Amazonian forests allocate productivity among its above- and below-ground components? (2 How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha−1 yr−1 (mean±standard error, at a white sand plot, and 17.0±1.4 Mg C ha−1 yr−1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha−1 yr−1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  3. 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.  

  4. Endophytic benefit for a competitive host is neutralized by increasing ratios of infected plants

    Science.gov (United States)

    Wu, Lianjie; Ren, Anzhi; Jing, Yuanfang; Zhou, Yong; Wang, Xinyu; Qin, Junhua; Gao, Yubao

    2016-01-01

    Leaf endophytes such as Epichloë can affect the competitive ability of host grasses, but the reported responses are inconsistent. We hypothesized that this inconsistency is caused, at least in part, by the following two aspects. One is that a competitive advantage might occur as a result of an increase in storage compounds for both growth and defense. Another is that the effect of the endophyte might be related to both water availability and host density. In a greenhouse experiment, we compared the competitive abilities of endophyte-infected (EI) and endophyte-free (EF) Leymus chinensis, a dominant grass native to the Inner Mongolia Steppe of China, subjected to ten treatments comprised of a factorial combination of two levels of water availability (well-watered and drought) and five proportions of EI to EF plants (12:0, 4:8, 6:6, 8:4, 0:12). The results showed that the competitive ability of EI plants was higher than that of EF under drought. Here, greater belowground biomass and water use efficiency might contribute to better competitiveness of EI plants. When competing under well-watered conditions, endophyte infection did not provide a benefit to the host plant in biomass accumulation, but more carbon was allocated to defense (total phenolics) in EI plants. This scenario could help EI plants suffer less damage than EF when exposed to herbivores in natural habitats. The competitive ability of EI plants was regulated by EI:EF ratios. Competitive ability of EI plants was higher than that of EF plants in mixtures with lower numbers of EI plants, but the beneficial effect of endophyte infection was neutralized in mixtures with higher numbers of EI plants. Overall, endophyte infection improved the competitive ability of the host under either drought or well-watered conditions but in the presence of herbivore, only this benefit was neutralized by increasing ratios of EI plants. We suspect that both the conditional beneficial effects and stabilizing effects of density

  5. Adsorption of carbamazepine by carbon nanotubes: Effects of DOM introduction and competition with phenanthrene and bisphenol A

    International Nuclear Information System (INIS)

    Carbon nanotubes, organic contaminants and dissolved organic matter (DOM) are co-introduced into the environment. Thus, the interactions between these components have to be evaluated to better understand their environmental behavior. In this study, single-walled carbon nanotubes (SWCNTs) were used as sorbent, carbamazepine was the primary adsorbate, and bisphenol A and phenanthrene were used as competitors. Strong competition with bisphenol A and no effect of phenanthrene on adsorption of carbamazepine was obtained. The hydrophobic neutral fraction of the DOM exhibited the strongest reductive effect on carbamazepine adsorption, most probably due to interactions in solution. In contrast, the hydrophobic acid fraction decreased carbamazepine adsorption mainly via direct competition. When DOM and bisphenol A were co-introduced, the adsorption of carbamazepine was significantly reduced. This study suggests that the chemical nature of DOM can significantly affect the sorptive behavior of polar organic pollutants with carbon nanotubes when all are introduced to the aquatic system. Highlights: •Bisphenol A is an efficient competitor for carbamazepine. •Phenanthrene does not compete with carbamazepine. •DOM exhibited strong reductive effect on carbamazepine adsorption by SWCNTs. •HoN fraction decreased carbamazepine adsorption due to interactions in solution. •HoA fraction decreased carbamazepine adsorption via direct competition. -- In multi-component system including the main adsorbate and competitor, DOM exhibited significant effect on adsorption of contaminants by carbon nanotubes

  6. Screening of Highly Effective Sinorhizobium meliloti Strains for 'Vector' Alfalfa and Testing of Its Competitive Nodulation Ability in the Field

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhao-Hai; CHEN Wen-Xin; HU Yue-Gao; SUI Xin-Hua; CHEN Dan-Ming

    2007-01-01

    Seventeen Sinorhizobium meliloti strains from seven provinces in China were used to screen highly effective strains for alfalfa cultivar in a greenhouse study and their symbiotic relationship and competitive ability were studied in the field.CCBAU30138 was the most effective strain,as evidenced by increase in dry weights.A field experiment showed that the inoculation of alfalfa with CCBAU30138 resulted in increases of 11.9%and 19.6%of dry matter production and crude protein production,respectively,in forage of monocultured plants.The total dry matter yields of alfalfa and tall fescue in binary culture were increased by 16.3%by inoculation of alfalfa with this strain.These results showed that S.Meliloti strain CCBAU30138 was an effective inoculant both in the greenhouse and in the field.The analysis of randomly amplified polymorphic DNA(RAPD)by polymerase chain reaction(PCR)from nodule extracts showed that the strain CCBAU30138 had high competitiveness in the field.It occupied 47.5%of nodules in alfalfa monoculture and 44.4% of nodules in alfalfa-tall fescue binary culture after 20 weeks of growth.In conclusion,a simple system to select highly effective and competitive symbiotic strains specific to alfalfa was established.Using this system.A strain suitable for the alfalfa cultivar'Vector’grown in Wuqiao County of Hebei Province was obtained.

  7. Does the relative importance of resource competition and architectural effect in floral variation vary with stages of floral ontogeny?

    Institute of Scientific and Technical Information of China (English)

    Chang-Qiu LIU; Shuang-Quan HUANG

    2012-01-01

    Variation in floral allocation within inflorescences has been attributed to resource competition and/or architectural effect.The two hypotheses were extensively studied and both hypotheses were partly supported by previous studies.However,the relative importance of resource competition and architectural effect may vary with stages of floral ontogeny in a species.To detect the effects ofontogenetic stages on floral variation,we manipulated the 6-flowered inflorescences ofAdenophorajasionifolia (Campanulaceae) by early,late,and non-thinning flowers.Our results indicated that pollen and ovule production of the remaining flowers were not significantly different between early and late thinning manipulations,suggesting that floral sex allocation was determined far before flowering,in support of the architectural effect hypothesis.Under hand-pollination treatments,early thinning but not late thinning resulted in a significant increase in seed number and seed set of the remaining flowers.Therefore,the increase in seed production of the remaining flowers related to the floral ontogeny.The resource competition for floral allocation was significant under early thinning rather than late thinning manipulation.Our results suggest that studies on floral variation within inflorescences should take into account the stages of floral ontogeny.

  8. 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 structure....... On the contrary, inferences based on the x-inefficiency literature suggest the highest positive effect will be experienced by companies with inappropriate ownership structure. Our empirical analysis on a panel of Czech firms shows that the former view is supported if import competition is high...

  9. 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.

  10. 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

  11. Competitive effects and instruments of power sector reforms. International reform concepts blockade structures, risk distribution. A political economy analysis

    International Nuclear Information System (INIS)

    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.

  12. STEM Clubs and Science Fair Competitions: Effects on Post-Secondary Matriculation

    Science.gov (United States)

    Sahin, Alpaslan

    2013-01-01

    As the global economic competition gets tougher, American policymakers and researchers are interested in finding ways to increase the number of students pursuing STEM (Science, Technology, Engineering, and Mathematics)-related majors in order for the United States to continue its role as an economic powerhouse. A survey study was employed to…

  13. 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

    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...

  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. Market Competition in Upper Secondary Education: Perceived Effects on Teachers' Work

    Science.gov (United States)

    Lundstrom, Ulf; Holm, Ann-Sofie

    2011-01-01

    The development and expansion of market solutions is one of the most important changes in Swedish education in the last 30 years. The aim of the article is to describe and analyse how students and staff in upper secondary schools perceive the impact of market competition on teachers' work. Three groups of actors in two Swedish regions were…

  16. 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 environme

  17. Enzymatic degradation of plant cell wall polysaccharides: the kinetic effect of competitive adsorption

    DEFF Research Database (Denmark)

    Bergsøe, Merete Norsker; Bloch, Line; Adler-Nissen, Jens

    1999-01-01

    when any of the monocomponent enzymes are added. To describe the results a new model designated 'the competitive activity adsorption model' is proposed. The model is based on the fact that the enzymes are adsorbed to the substrate before action. A combination of the Langmuir adsorption isotherm...

  18. The Effects of Railway Investments in a Polycentric City: A Comparison of Competitive and Segmented Land Markets

    OpenAIRE

    Debrezion, G.; Pels, E.; Rietveld, P.

    2007-01-01

    The paper analyzes the effect of railway investment on land prices and land use in a polycentric city under various regulatory regimes of land markets. The introduction of a fast mode of transport (train), accessible in discrete locations, leads to an increase in city size. The stations of the fast mode induce dense residential settlements in their vicinity. As a result, the average residential and commercial land rents increase in both competitive and segmented land-market situations, compar...

  19. Effectiveness of 14-15 years old tennis players’ competition functioning considering correction of their psychological fitness

    OpenAIRE

    Makuts T.B.

    2015-01-01

    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 det...

  20. Effects of state anxiety on music performance: Relationship between the Revised Competitive State Anxiety Inventory-2 subscales and piano performanc

    OpenAIRE

    Yoshie, M.; Shigemasu, K.; Kudo, K.; Ohtsuki, T.

    2009-01-01

    This study investigated the relationship between the Revised Competitive State Anxiety Inventory-2 (CSAI-2R, Cox, Martens, & Russell, 2003; Jones & Swain, 1992; Martens, Vealey, & Burton, 1990) subscales and the quality of music performance to compare the anxiety-performance relationship in pianists with that in athletes and to gain insights into the effective coping strategies for music performance anxiety (MPA). Fifty one students (15 women and 36 men) aged 18-26 years (M = 20.6, SD = 2.3) ...

  1. Effect of naloxone on food competition aggression in food-restricted high and low aggression pigeons (Columba livia)

    OpenAIRE

    Fachinelli C.; Torrecillas M.; Rodríguez Echandía E.L.

    2004-01-01

    We determined the effect of the opiate receptor antagonist naloxone on aggression, emotion, feeder control, and eating behavior in high and low aggression female pigeons maintained at 80% of their normal weight and exposed to food competition interactions. Pigeons were divided into pairs by previously ranked high aggression (total time spent in offensive aggression exceeding 60 s/5 min; N = 6 pairs) and low aggression females (time spent in offensive aggression less than 10 s/5 min; N = 6 pai...

  2. Extinction in periodic competitive stage-structured Lotka-Volterra model with the effects of toxic substances

    Science.gov (United States)

    Li, Zhong; Chen, Fengde

    2009-09-01

    In this paper, we consider a periodic competitive stage-structured Lotka-Volterra model with the effects of toxic substances. It is shown that toxic substances play an important role in the extinction of species. We obtain a set of sufficient conditions which guarantee that one of the components is driven to extinction while the other is globally attractive. The numerical simulation of an example verifies our main results.

  3. The Effect of Information Technology on Competitive Advantage: Case of Food and Beverage Industry in South Sulawesi Province, Indonesia

    OpenAIRE

    Munizu, Musran

    2013-01-01

    This study attempt to investigate the effect of Information Technology (IT) on competitive advantage, especially food and beverage industry in South Sulawesi, Indonesia. The research use survey approach and data was collected by questionnaire. The unit of analysis is big and medium scale companies. The respondents this research are the managers of companies. There were 126 companies were surveyed and total of 100 completed questionnaires were returned as the final sample. Two hypotheses have ...

  4. 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.

  5. Belowground heathland responses after 2 years of combined warming, elevated CO2 and summer drought

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Michelsen, Anders; Ambus, Per;

    2010-01-01

    significantly to the treatments. In the combined temperature and CO2 treatment the dissolved organic nitrogen concentration decreased and the ammonium concentration increased, but this release of nutrients was not mirrored by plant parameters. Microbial biomass carbon and microbial enrichment with 13C and 15N...... (1 year after 13C215N-glycine was injected into the soil) increased in warmed plots and in elevated CO2 plots, but not when these treatments were combined. Furthermore, drought led to an increase in Calluna biomass and total plant nitrogen pool. The full combination of warming, elevated CO2...... belowground sequestration of labile carbohydrates due to elevated CO2 in combination with temperature increased process rates. Together, these changes might increase microbial activity and availability of plant nutrients. Two years after the start of the experiment, belowground processes responded...

  6. The effect of direct interspecific competition on patch exploitation strategies in parasitoid wasps.

    Science.gov (United States)

    Mohamad, Rihab; Wajnberg, Eric; Monge, Jean-Paul; Goubault, Marlène

    2015-01-01

    The presence of competitors may affect the pay-off of individuals' foraging strategies. They should therefore modify their resource exploitation decisions accordingly. In such a direct competition situation, theory predicts that individuals should stay longer on a resource patch than when foraging alone. However, models predicting patch residence time focus on intraspecific competition without agonistic interactions. Here, we investigate the patch use strategies of females of two parasitoid species, Eupelmus vuilleti and Dinarmus basalis, attacking the same host, Callosobruchus maculatus, knowing that D. basalis is more aggressive and can exclude E. vuilleti during pairwise contests for single hosts. Our results showed that time allocation and oviposition strategies differed in relation to the species and type of competition (i.e., presence/absence of competitor, simultaneous/sequential female introduction or resident/intruder female). Eupelmus vuilleti females tended to wait in the patch surroundings for D. basalis females' departure to return and exploit hosts parasitized by the opponent (after destruction of her eggs). In contrast, D. basalis females tended to self-superparasitize and stay motionless near the hosts. After detecting an E. vuilleti female entering the patch, they attacked and chased her permanently from the patch. Females of both species spent less time in the patch when faced with a competitor than when alone. This study is the first to test the influence of direct interspecific competition and arrival order on patch exploitation strategies in parasitoid species, and highlights the necessity to include agonistic behaviors in theoretical models predicting optimal patch residence time in competitive situations.

  7. Competition and coexistence between a syntrophic consortium and a metabolic generalist, and its effect on productivity.

    Science.gov (United States)

    Stump, Simon M; Klausmeier, Christopher A

    2016-09-01

    Syntrophic interactions, where species consume metabolites excreted by others, are common in microbial communities, and have uses in synthetic biology. Syntrophy is likely to arise when trade-offs favor an organism that specializes on particular metabolites, rather than all possible metabolites. Several trade-offs have been suggested; however, few models consider different trade-offs to test which are most consistent with observed patterns. Here, we develop a differential equation model to study competition between a syntrophic processing chain, where each microbe can perform one step in metabolizing an initial resource to a final state, and a metabolic generalist that can perform all metabolic functions. We also examine how competition affects the production of the final metabolic compound. We find that competitive outcomes can be predicted by a generalization of the R(⁎)-rule and relative nonlinearity. Therefore, the species that can persist at the lowest resource level is the competitive dominant in a constant environment, and species can coexist by partitioning variation in resources. We derive a simple rule for predicting production rates of the final metabolite, and show that competition may not maximize final metabolite production. We show that processing chains are inherently less efficient, because resources are lost during each step of the process. Our results also suggest which trade-offs are capable of explaining certain empirical observations. For example, processing chains appear to be more common in nutrient-rich environments; our model suggests that a specificity trade-off and an affinity-yield trade-off would not predict this, but a yield-maximum growth trade-off might. PMID:27320679

  8. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    OpenAIRE

    L. E. O. C. Aragão; Malhi, Y.; Metcalfe, D.B; Silva-Espejo, J. E.; E. Jiménez; Navarrete, D.; Almeida, S.; Costa, A. C. L.; N. Salinas; O. L. Phillips; L. O. Anderson; Alvarez, E.; T. R. Baker; P. H. Goncalvez; J. Huamán-Ovalle

    2009-01-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quanti...

  9. Below-ground herbivory limits induction of extrafloral nectar by above-ground herbivores

    OpenAIRE

    Huang, Wei; Siemann, Evan; Carrillo, Juli; Ding, Jianqing

    2015-01-01

    Background and Aims Many plants produce extrafloral nectar (EFN), and increase production following above-ground herbivory, presumably to attract natural enemies of the herbivores. Below-ground herbivores, alone or in combination with those above ground, may also alter EFN production depending on the specificity of this defence response and the interactions among herbivores mediated through plant defences. To date, however, a lack of manipulative experiments investigating EFN production induc...

  10. Belowground ectomycorrhizal fungal communities at fagus stands in differently polluted forest research plots

    OpenAIRE

    Al Sayegh-Petkovšek, Samar

    2005-01-01

    Belowground ectomycorrhizal fungal communities at fagus stands were analysed. Eectomycorrhiza types were identified in soil cores from differently polluted beech forest research plots in the 1998 - 2001 period by mycobioindication method. Forest research plots were situated in the vicinity of thermal power plants (polluted plots: Zavodnje - Prednji vrh and Zasavje - Dobovec) and in unpolluted areas (in the vicinity of Kočevska Reka: Preža and Moravške gredice). Eighty-eight different ectomyco...

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

    OpenAIRE

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

    2015-01-01

    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 do...

  12. Above- and below-ground responses of Calamagrostis purpurea to UV-B radiation and elevated CO{sub 2} under phosphorus limitation

    Energy Technology Data Exchange (ETDEWEB)

    Bussell, J.S.; Gwynn-Jones, D.; Griffith, G.W.; Scullion, J. (Aberystwyth Univ., IBERS, Wales (United Kingdom))

    2012-08-15

    UV-B radiation and elevated CO{sub 2} may impact rhizosphere processes through altered below-ground plant resource allocation and root exudation, changes that may have implications for nutrient acquisition. As nutrients limit plant growth in many habitats, their supply may dictate plant response under elevated CO{sub 2}. This study investigated UV-B exposure and elevated CO{sub 2} effects, including interactions, on plant growth, tissue chemistry and rooting responses relating to P acquisition. The sub-arctic grass Calamagrostis purpurea was subjected to UV-B (0 or 3.04 kJ m-2day-1) and CO{sub 2} (ambient 380 or 650 ppmv) treatments in a factorial glasshouse experiment, with sparingly soluble P (0 or 0.152 mg P per plant as FePO{sub 4}) a further factor. It was hypothesized that UV-B exposure and elevated CO{sub 2} would change plant resource allocation, with CO{sub 2} mitigating adverse responses to UV-B exposure and aiding P uptake. Plant biomass and morphology, tissue composition and rhizosphere leachate properties were measured. UV-B directly affected chemical composition of shoots and interacted with CO{sub 2} to give a greater root biomass. Elevated CO{sub 2} altered the composition of both shoots and roots and increased shoot biomass and secondary root length, while leachate pH decreased. Below-ground responses to CO{sub 2} did not affect P acquisition although P limitation progressively reduced leachate pH and increased secondary root length. Although direct plant growth, foliar composition and below-ground nutrient acquisition responses were dominated by CO{sub 2} treatments, UV-B modified these CO{sub 2} responses significantly. These interactions have implications for plant responses to future atmospheric conditions. (Author)

  13. The influence of male parr body size and mate competition on fertilization success and effective population size in Atlantic salmon.

    Science.gov (United States)

    Jones, M W; Hutchings, J A

    2001-06-01

    Alternative mating strategies in male Atlantic salmon, Salmo salar, are characterized by variability in body size and mate competition. Controlling breeding numbers of larger, older anadromous males, we examined whether body size of mature male parr influenced fertilization success and whether such an association was affected by mate competition among parr. Variation at three to four hypervariable microsatellite loci was used to determine individual paternity of 53-60 offspring from two or three nests from each experimental treatment. Although individual and total parr reproductive success differed significantly among nests within treatments, there was no relationship between parr size and individual reproductive success at any level of competition when anadromous males were involved. However, in a single treatment having no anadromous male, the influence of body size on parr fertilization success was highly significant. Combining data from all treatments, parr body size was an important predictor of the probability of an individual being involved in spawning. We found a negative relationship between total parr reproductive success and intensity of anadromous male competition. To our knowledge, the present study is the first to estimate the effective number of males from individual fertilization success in fish. Our estimates of Ne should not be taken as absolute and may have a downward bias because we did not sample all nests and we used a proxy for lifetime reproductive success. They do, however, illustrate how mature male parr can greatly increase the effective number of males when the latter is estimated from anadromous individuals alone. Although reproductive success by mature male parr increases the effective number of males, this increase seems likely to be most pronounced in natural populations when the number of anadromous males is low.

  14. Existence and stability of almost periodic solutions of nonautonomous competitive systems with weak Allee effect and delays

    Science.gov (United States)

    Wu, Wanqin; Ye, Yuan

    2009-11-01

    In this paper, a class of nonautonomous Lotka-Volterra type multispecies competitive systems with weak Allee effect and delays are considered. By using Mawhin's continuation theorem of coincidence degree theory, we obtain some sufficient conditions for the existence of almost periodic solutions for the Lotka-Volterra system. On the case of no delays of Allee effects, by constructing a suitable Lyapunov function, we get a sufficient condition for the globally attractivity of the almost periodic solution for the Lotka-Volterra system. Moreover, we also present an illustrative example to show the effectiveness of our results.

  15. Imaging spectroscopy links aspen genotype with below-ground processes at landscape scales.

    Science.gov (United States)

    Madritch, Michael D; Kingdon, Clayton C; Singh, Aditya; Mock, Karen E; Lindroth, Richard L; Townsend, Philip A

    2014-01-01

    Fine-scale biodiversity is increasingly recognized as important to ecosystem-level processes. Remote sensing technologies have great potential to estimate both biodiversity and ecosystem function over large spatial scales. Here, we demonstrate the capacity of imaging spectroscopy to discriminate among genotypes of Populus tremuloides (trembling aspen), one of the most genetically diverse and widespread forest species in North America. We combine imaging spectroscopy (AVIRIS) data with genetic, phytochemical, microbial and biogeochemical data to determine how intraspecific plant genetic variation influences below-ground processes at landscape scales. We demonstrate that both canopy chemistry and below-ground processes vary over large spatial scales (continental) according to aspen genotype. Imaging spectrometer data distinguish aspen genotypes through variation in canopy spectral signature. In addition, foliar spectral variation correlates well with variation in canopy chemistry, especially condensed tannins. Variation in aspen canopy chemistry, in turn, is correlated with variation in below-ground processes. Variation in spectra also correlates well with variation in soil traits. These findings indicate that forest tree species can create spatial mosaics of ecosystem functioning across large spatial scales and that these patterns can be quantified via remote sensing techniques. Moreover, they demonstrate the utility of using optical properties as proxies for fine-scale measurements of biodiversity over large spatial scales.

  16. 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.

  17. Comparing the effectiveness of individualistic, altruistic, and competitive incentives in motivating completion of mental exercises.

    Science.gov (United States)

    Schofield, Heather; Loewenstein, George; Kopsic, Jessica; Volpp, Kevin G

    2015-12-01

    This study examines the impact of individually oriented, purely altruistic, and a hybrid of competitive and cooperative monetary reward incentives on older adults' completion of cognitive exercises and cognitive function. We find that all three incentive structures approximately double the number of exercises completed during the six-week active experimental period relative to a no incentive control condition. However, the altruistic and cooperative/competitive incentives led to different patterns of participation, with significantly higher inter-partner correlations in utilization of the software, as well as greater persistence once incentives were removed. Provision of all incentives significantly improved performance on the incentivized exercises. However, results of an independent cognitive testing battery suggest no generalizable gains in cognitive function resulted from the training. PMID:26595894

  18. The effect of virus-blocking Wolbachia on male competitiveness of the dengue vector mosquito, Aedes aegypti.

    Directory of Open Access Journals (Sweden)

    Michal Segoli

    2014-12-01

    Full Text Available 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.

  19. Lethal effects of habitat degradation on fishes through changing competitive advantage

    OpenAIRE

    McCormick, Mark I.

    2012-01-01

    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 ...

  20. 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 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 sprint times in either men or women. In addition, hand timing may not always produce faster times compared to electronic timing.

  1. EFFECTIVE TEAMWORK AND LEADERSHIP, THE KEY TO GAINING COMPETITIVE EDGE IN THE NOWADAYS SERVICE INDUSTRY

    OpenAIRE

    Theodor Valentin Purcarea; Monica Paula Ratiu

    2011-01-01

    Our paper is intended to present the critical role of the service organizations’ members represented by personnel (employees) in creating competitive advantage and driving growth and value. In order to face current economic challenges managers acting in the services industry need to recognize the importance of motivation and involvement of employees materialized in service team performance; also, leaders’ creativity influences the service organizations’ performance in the global business envi...

  2. Intraspecific competition in the ant Camponotus cruentatus: should we expect the 'dear enemy' effect?

    OpenAIRE

    Boulay, Raphaël; CERDÁ, XIM; Simon, Tovit; Roldan, María; Hefetz, Abraham

    2007-01-01

    The mechanisms of competition and resource domination were analysed in the Mediterranean ant Camponotus cruentatus. In a plot located in southern Spain mature colonies are overdispersed, which is indicative of territoriality in other species. Unexpectedly, however, workers from neighbouring colonies commonly foraged in areas that overlapped by more than 44%. This suggests that while mature colonies possibly prevent the establishment of new colonies in the vicinity of their nests, they do not ...

  3. Structural and Infrastructural Practices as Elements of Content Operations Strategy. The Effect on Firm Competitiveness

    OpenAIRE

    Diaz-Garrido, Eloisa; Martin-Peña, Maria Luz; Garcia-Muina, Fernando

    2007-01-01

    Abstract Some extant theoretical studies and different empirical results demonstrate that firms? behaviour explains several notable competitiveness microeconomic foundations, based on a wide bundle of elements. Most of these elements can directly be controlled by firms; in this paper we focus on those related to operations management. So, products, processes, technology, equipments or quality control systems will centre our attention. These ones and some additional elements constit...

  4. 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.

  5. Epigenetic effects on personality traits: early food provisioning and sibling competition

    OpenAIRE

    Carere, C; Drent, PJ; Koolhaas, JM; Groothuis, TGG; Drent, Piet J.; Koolhaas, Jaap M.; Groothuis, Ton G.G

    2005-01-01

    The relative contribution of genetic and non-genetic factors in shaping personality traits is of fundamental relevance to biologists and social scientists. Individual animals vary in the way they cope with challenges in their environment, comparable with variation in human personalities. This variation has a substantial genetic basis. Here we describe experiments showing the strength of environmental factors (food availability and sibling competition) in shaping personality traits in a passer...

  6. Advancing Understanding of the Role of Belowground Processes in Terrestrial Carbon Sinks trhrough Ground-Penetrating Radar. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Day, Frank P. [Old Dominion Univ., Norfolk, VA (United States)

    2015-02-06

    Coarse roots play a significant role in belowground carbon cycling and will likely play an increasingly crucial role in belowground carbon sequestration as atmospheric CO2 levels continue to rise, yet they are one of the most difficult ecosystem parameters to quantify. Despite promising results with ground-penetrating radar (GPR) as a nondestructive method of quantifying biomass of coarse roots, this application of GPR is in its infancy and neither the complete potential nor limitations of the technology have been fully evaluated. The primary goals and questions of this study fell into four groups: (1) GPR methods: Can GPR detect change in root biomass over time, differentiate live roots from dead roots, differentiate between coarse roots, fine roots bundled together, and a fine root mat, remain effective with varied soil moisture, and detect shadowed roots (roots hidden below larger roots); (2) CO2 enrichment study at Kennedy Space Center in Brevard County, Florida: Are there post-fire legacy effects of CO2 fertilization on plant carbon pools following the end of CO2application ? (3) Disney Wilderness Study: What is the overall coarse root biomass and potential for belowground carbon storage in a restored longleaf pine flatwoods system? Can GPR effectively quantify coarse roots in soils that are wetter than the previous sites and that have a high percentage of saw palmetto rhizomes present? (4) Can GPR accurately represent root architecture in a three-dimensional model? When the user is familiar with the equipment and software in a setting that minimizes unsuitable conditions, GPR is a relatively precise, non-destructive, useful tool for estimating coarse root biomass. However, there are a number of cautions and guidelines that should be followed to minimize inaccuracies or situations that are untenable for GPR use. GPR appears to be precise as it routinely predicts highly similar values for a given area across multiple

  7. Competition Regime

    OpenAIRE

    Danilo Icaza Ortiz

    2013-01-01

    This paper is a review of the competition regime works of various authors, published under the auspices of the University of the Hemispheres and the Corporation for Studies and Publications. Analyzes the structure, the general concepts, case law taken for development. Includes comments on the usefulness of this work for the study of competition law and the contribution to the lawyers who want to practice in this branch of economic law.

  8. Competition Regime

    Directory of Open Access Journals (Sweden)

    Danilo Icaza Ortiz

    2013-01-01

    Full Text Available This paper is a review of the competition regime works of various authors, published under the auspices of the University of the Hemispheres and the Corporation for Studies and Publications. Analyzes the structure, the general concepts, case law taken for development. Includes comments on the usefulness of this work for the study of competition law and the contribution to the lawyers who want to practice in this branch of economic law.

  9. Companies Export Function: Identifying the Effects of Perceived Competitive Advantages, Adapting Marketing Tactics and Exporting Experience on Export Function

    Directory of Open Access Journals (Sweden)

    Yaghoub Hossainee

    2011-07-01

    Full Text Available Abstract Information and communication technology (ICT has intensively affected the quality and quantity of competition among companies in their accessibility to the markets of other countries during the last two decades. The basic question that every company working in the international markets has faced with is the factors affecting export function. This study is conducted for the purpose of answering this question. Reviewing the related literature shows that among many factors which may affect export function, adapting marketing tactics, export experience, and perceived competitive advantage are the most remarkable ones. Based on this theoretical finding, the conceptual model of the research had created and five hypotheses were tested during this study. For adopting experimental data with the conceptual model, export companies in Fars province have been studied. Findings illustrate that four out of five hypotheses of the research have approved and only the direct relationship of marketing tactics adaption with export function has not been verified. The effect of marketing tactics adoption to export function was indirect and obtained through perceived competitive advantage as an intermediary variable.

  10. Companies Export Function: Identifying the Effects of Perceived Competitive Advantages, Adapting Marketing Tactics and Exporting Experience on Export Function

    Directory of Open Access Journals (Sweden)

    S. Y. Hosseini

    2011-01-01

    Full Text Available Information and communication technology (ICT has intensively affected the quality and quantity of competition among companies in their accessibility to the markets of other countries during the last two decades. The basic question that every company working in the international markets has faced with is the factors affecting export function. This study is conducted for the purpose of answering this question. Reviewing the related literature shows that among many factors which may affect export function, adapting marketing tactics, export experience, and perceived competitive advantage are the most remarkable ones. Based on this theoretical finding, the conceptual model of the research had created and five hypotheses were tested during this study. For adopting experimental data with the conceptual model, export companies in Fars province have been studied. Findings illustrate that four out of five hypotheses of the research have approved and only the direct relationship of marketing tactics adaption with export function has not been verified. The effect of marketing tactics adoption to export function was indirect and obtained through perceived competitive advantage as an intermediary variable.

  11. 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. PMID:27208810

  12. The effect of age on the mating competitiveness of male Glossina fuscipes fuscipes and G. palpalis palpalis

    Directory of Open Access Journals (Sweden)

    P.P. Abila

    2003-05-01

    Full Text Available The effect of age on male Glossina fuscipes fuscipes, Newstead, and Glossina palpalis palpalis, Austin (Diptera: Glossinidae competiveness were investigated with a view to estimate optimal age for sterile male release. Sterile insect technique involves the mass production, sterilization and sequential release of males of the target species to out compete the wild male population. Mating between released sterile males and wild females produce inviable progeny and the population is reduced over several generations to unsustainable levels. It is vital that the released male are of high quality and are sexually competitive. Age is one parameter affecting the sexual competiveness of the male tsetse fly. The optimal release age was estimated by assessing sexual competitiveness of flies of different age categories, 1, 5, 8 and 13-days after adult eclosion. A walk-in field-cage was used in order to approximate as closely as possible the actual field scenario during sterile insect release programes. It was shown that 8 and 13-day old males mated significantly more frequently, i.e. were more competitive, in the presence of equal numbers of 1 and 5-day old males. The age of male tsetse flies significantly affected competitiveness in both species studied. The ability of G. f. fuscipes to inseminate was not age dependent, and insemination occurred in all females that mated regardless of male age. In G. p. palpalis, however, 1-day old males were least able to inseminate. Mating duration was not significantly affected by age in both species. Eight to thirteen day old males of the test species are here recommended as the optimal sterile male release age.

  13. Effects of a seven day overload-period of high-intensity training on performance and physiology of competitive cyclists.

    Directory of Open Access Journals (Sweden)

    Bradley Clark

    Full Text Available Competitive endurance athletes commonly undertake periods of overload training in the weeks prior to major competitions. This investigation examined the effects of two seven-day high-intensity overload training regimes (HIT on performance and physiological characteristics of competitive cyclists.The study was a matched groups, controlled trial.Twenty-eight male cyclists (mean ± SD, Age: 33±10 years, Mass 74±7 kg, VO2 peak 4.7±0.5 L·min-1 were assigned to a control group or one of two training groups for seven consecutive days of HIT. Before and after training cyclists completed an ergometer based incremental exercise test and a 20-km time-trial. The HIT sessions were ∼120 minutes in duration and consisted of matched volumes of 5, 10 and 20 second (short or 15, 30 and 45 second (long maximal intensity efforts.Both the short and long HIT regimes led to significant (p0.05 increases (mean ± SD in VO2 peak (2.3%±4.7% vs 3.5%±6.2%, lactate threshold power (3.6%±3.5% vs 2.9%±5.3% and gross efficiency (3.2%±2.4% vs 5.1%±3.9% with only small differences between HIT regimes.Seven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists.

  14. 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

  15. 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.

  16. Influence of trivalent electrolytes on the humic colloid-borne transport of contaminant metals: competition and flocculation effects

    Science.gov (United States)

    Lippold, H.; Mansel, A.; Kupsch, H.

    2005-02-01

    With the objective to assess the relevance of competitive effects in respect of the humic colloid-borne migration of actinides in case of release, the influence of Al(III) on humate complexation of La(III) as an analogue of trivalent actinides was investigated for various humic materials by using 140La as a radioactive tracer, allowing measurements in very dilute systems to simulate realistic settings. Generally, competition by aluminium is not detectable unless the metal-loading capacity of the humic colloids is nearly exhausted. For average contents of organic carbon, a threshold value of 10 -6 M Al(III) can be specified. The metal exchange turned out to be kinetically hindered. Effects on co-adsorption of La(III) and humic acid were found to be less important. Immobilization by the concomitantly induced flocculation process outweighs the role of displacement effects. Comparative studies on complexation and flocculation of humic acid with Al(III), Ga(III), In(III), Sc(III), Y(III), and La(III) were undertaken in order to evaluate the influence of specific properties apart from ion charge and to characterize the mechanism of flocculation. In spite of considerable variations in the binding affinities among these metals, it can be inferred that the possibility of significant competitive effects in natural aquatic systems is confined to Al(III). Complex stabilities and flocculation efficiencies proved to be interrelated. Precipitation is thus attributed to homocoagulation of humic colloids induced by charge compensation, which is further supported by flocculation experiments with Al(III) depending on pH, ionic strength, and humic acid concentration.

  17. Global Competitiveness Index and economic growth

    OpenAIRE

    Cazacu, Ana-Maria

    2015-01-01

    In this paper, we examine the linkage between economic growth and competitiveness on a panel of 28 European countries, during 2006-2013. We use Global Competitiveness Index (GCI) as a measure of national competitive capacities and find that a shock in competitiveness has a positive impact on GDP developments. Nevertheless, the results show that fast economic growth has a small positive effect on competitiveness, as increasing the competitive capacity of a nation is linked to many other factor...

  18. The Developmental Aspects and Origins of Competitive Behavior in Children.

    Science.gov (United States)

    Blanchard, Charles W.

    The literature on competitive behavior in children is examined. Sections of the review concern the socializing process of competitiveness, evolutionary foundations, early developmental processes, the relationship between competition and aggression, gender differences, competition and cooperation, anthropological perspectives, effects of…

  19. The Liberalisation of the Postal Service Market in Estonia and its Effect on Competition

    Directory of Open Access Journals (Sweden)

    Jüri Sepp

    2013-01-01

    Full Text Available The liberalisation of infrastructure sectors through opening up markets as a method for increasing the efficiency of infrastructure services is an international tendency. Emerging competition has been seen as an essential element in this process. On the other hand, the liberalisation of the market for universal services can cause several problems in ensuring quality and access to services. In this article we evaluate the results of liberalisation in the Estonian postal sector as an infrastructure specific sector offering a universal service in a decreasing market in a small country.

  20. Competitive Reactions and the Cross-Sales Effects of Advertising and Promotion

    OpenAIRE

    Steenkamp, Jan-Benedict; Nijs, V.R.; Hanssens, Dominique; Dekimpe, Marnik

    2002-01-01

    textabstractHow do competitors react to each other's price-promotion and advertising actions? How do these reactions influence the net sales impact we observe? We answer these questions by performing a large-scale empirical study of the short-run and long-run reactions to promotion and advertising shocks in over 400 consumer product categories, over a four-year time span. Competitive reaction can be passive, accommodating or retaliatory. We first develop a series of expectations on the type a...

  1. Non-mean-field effects in systems with long-range forces in competition.

    Science.gov (United States)

    Bachelard, R; Staniscia, F

    2012-11-01

    We investigate the canonical equilibrium of systems with long-range forces in competition. These forces create a modulation in the interaction potential and modulated phases appear at the system scale. The structure of these phases differentiate this system from monotonic potentials, where only the mean-field and disordered phases exist. With increasing temperature, the system switches from one ordered phase to another through a first-order phase transition. Both mean-field and modulated phases may be stable, even at zero temperature, and the long-range nature of the interaction will lead to metastability characterized by extremely long time scales.

  2. Diversity of larger consumers enhances interference competition effects on smaller competitors.

    Science.gov (United States)

    Nascimento, Francisco J A; Karlson, Agnes M L; Näslund, Johan; Elmgren, Ragnar

    2011-06-01

    Competition between large and small species for the same food is common in a number of ecosystems including aquatic ones. How diversity of larger consumers affects the access of smaller competitors to a limiting resource is not well understood. We tested experimentally how species richness (0-3 spp.) of benthic deposit-feeding macrofauna changes meiofaunal ostracods' incorporation of fresh organic matter from a stable-isotope-labeled cyanobacterial bloom, using fauna from the species-poor Baltic Sea. Presence of macrofauna mostly decreased meiofaunal incorporation of bloom material, depending on the macrofauna species present. As expected, the species identity of macrofauna influenced the incorporation of organic matter by meiofauna. Interestingly, our results show that, in addition, species richness of the macrofauna significantly reduced meiofauna incorporation of freshly settled nitrogen and carbon. With more than one macrofauna species, the reduction was always greater than expected from the single-species treatments. Field data from the Baltic Sea showed a negative correlation between macrofauna diversity and meiofaunal ostracod abundance, as expected from the experimental results. We argue that this is caused by interference competition, due to spatial niche differentiation between macrofauna species reducing the sediment volume in which ostracods can feed undisturbed by larger competitors. Interference from macrofauna significantly reduces organic matter incorporation by meiofauna, indicating that diversity of larger consumers is an important factor controlling the access of smaller competitors to a limiting food resource.

  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. 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.

  5. 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)

  6. Competition Between Different Social Ranked Rams has Similar Effects on Testosterone and Sexual Behaviour Throughout the Year.

    Science.gov (United States)

    Ungerfeld, R; Lacuesta, L

    2015-12-01

    Dominant rams have preferential access to females, as they frequently interrupt sexual behaviour from subordinated. Testosterone concentrations are directly linked to sexual and aggressive behaviour and have important variations along the year. Therefore, it may be expected that the effects of dominance relationships on reproductive behaviour differ according to testosterone concentrations, and thus to the period of the year. The aim of this study was to compare the effects of dominance relationships on testosterone and sexual behaviour in different moments of the year in rams. Twelve rams were maintained in a single group. Social rank was determined in January (maximum reproductive development), May (regression of the reproductive status) and August (lowest reproductive activity), and the four rams with higher (HR) and the four with lower (LR) success index were used. Testosterone serum concentration was weekly measured four times during each experimental period. Sexual behaviour was evaluated in each period with an oestrous ewe, and with the oestrous ewe and another ram from the other social rank (each HR with each LR ram). Testosterone concentration was greater in HR than LR rams in January (p = 0.03), and all the behaviours were displayed more frequently in non-competitive than in competitive tests (p Rams modified their sexual strategy in competitive environments decreasing the display of sexual behaviour independently of their social status. This effect was observed consistently throughout the year: high-ranked rams have greater testosterone concentrations than LR rams only during the pre-rut, when they naturally compete to join the groups of ewes. PMID:26489705

  7. Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants.

    Science.gov (United States)

    Wu, Junen; Liu, Wenjie; Chen, Chunfeng

    2016-01-19

    Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ(18)O, and δ(13)C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ(18)O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ(13)C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer.

  8. Recovery of trees from drought depends on belowground sink control.

    Science.gov (United States)

    Hagedorn, Frank; Joseph, Jobin; Peter, Martina; Luster, Jörg; Pritsch, Karin; Geppert, Uwe; Kerner, Rene; Molinier, Virginie; Egli, Simon; Schaub, Marcus; Liu, Jian-Feng; Li, Maihe; Sever, Krunoslav; Weiler, Markus; Siegwolf, Rolf T W; Gessler, Arthur; Arend, Matthias

    2016-01-01

    Climate projections predict higher precipitation variability with more frequent dry extremes(1). CO2 assimilation of forests decreases during drought, either by stomatal closure(2) or by direct environmental control of sink tissue activities(3). Ultimately, drought effects on forests depend on the ability of forests to recover, but the mechanisms controlling ecosystem resilience are uncertain(4). Here, we have investigated the effects of drought and drought release on the carbon balances in beech trees by combining CO2 flux measurements, metabolomics and (13)CO2 pulse labelling. During drought, net photosynthesis (AN), soil respiration (RS) and the allocation of recent assimilates below ground were reduced. Carbohydrates accumulated in metabolically resting roots but not in leaves, indicating sink control of the tree carbon balance. After drought release, RS recovered faster than AN and CO2 fluxes exceeded those in continuously watered trees for months. This stimulation was related to greater assimilate allocation to and metabolization in the rhizosphere. These findings show that trees prioritize the investment of assimilates below ground, probably to regain root functions after drought. We propose that root restoration plays a key role in ecosystem resilience to drought, in that the increased sink activity controls the recovery of carbon balances. PMID:27428669

  9. 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.

  10. Functional soil microbiome: belowground solutions to an aboveground problem.

    Science.gov (United States)

    Lakshmanan, Venkatachalam; Selvaraj, Gopinath; Bais, Harsh P

    2014-10-01

    There is considerable evidence in the literature that beneficial rhizospheric microbes can alter plant morphology, enhance plant growth, and increase mineral content. Of late, there is a surge to understand the impact of the microbiome on plant health. Recent research shows the utilization of novel sequencing techniques to identify the microbiome in model systems such as Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). However, it is not known how the community of microbes identified may play a role to improve plant health and fitness. There are very few detailed studies with isolated beneficial microbes showing the importance of the functional microbiome in plant fitness and disease protection. Some recent work on the cultivated microbiome in rice (Oryza sativa) shows that a wide diversity of bacterial species is associated with the roots of field-grown rice plants. However, the biological significance and potential effects of the microbiome on the host plants are completely unknown. Work performed with isolated strains showed various genetic pathways that are involved in the recognition of host-specific factors that play roles in beneficial host-microbe interactions. The composition of the microbiome in plants is dynamic and controlled by multiple factors. In the case of the rhizosphere, temperature, pH, and the presence of chemical signals from bacteria, plants, and nematodes all shape the environment and influence which organisms will flourish. This provides a basis for plants and their microbiomes to selectively associate with one another. This Update addresses the importance of the functional microbiome to identify phenotypes that may provide a sustainable and effective strategy to increase crop yield and food security.

  11. The Effect of Forming a Score-Based Competitive System in a Cyber-Drilling Atmosphere for Learning and Motivation

    Directory of Open Access Journals (Sweden)

    Bekir ÇELEN

    2009-01-01

    Full Text Available This research focuses on to carry out a structure, in which the desire of having a high score and seeing the name in the top list is used in web-based drills and helps students to be more willing in test solving. The purpose of this study is to determine the effects of web-based drills on motivation and learning in a competitive atmosphere. Furthermore, the study also attempts to determine if the students’ levels and frequency of using a computer have an effect on the test scores in a web based system.Over a period of two week application students logged in the system using their own passwords and solve questions whenever they wanted. The names and photographs of the students who achieved the best scores were declared on the school’s website. In the study, an experimental design has been applied. The data were collected through the database in the web-based drill, pre and post survey to determine the level of and the reasons for students’ use of the website and history common exam results. According to the findings of the research, the website that has the competitive atmosphere has a positive effect on students’ achievement in their lessons. The application led to a change in students’ aim to visit the website and the frequency of their visits.

  12. Plants control the seasonal dynamics of microbial N cycling in a beech forest soil by belowground C allocation.

    Science.gov (United States)

    Kaiser, Christina; Fuchslueger, Lucia; Koranda, Marianne; Gorfer, Markus; Stange, Claus F; Kitzler, Barbara; Rasche, Frank; Strauss, Joseph; Sessitsch, Angela; Zechmeister-Boltenstern, Sophie; Richter, Andreas

    2011-05-01

    Soil microbes in temperate forest ecosystems are able to cycle several hundreds of kilograms of N per hectare per year and are therefore of paramount importance for N retention. Belowground C allocation by trees is an important driver of seasonal microbial dynamics and may thus directly affect N transformation processes over the course of the year. Our study aimed at unraveling plant controls on soil N cycling in a temperate beech forest at a high temporal resolution over a time period of two years, by investigating the effects of tree girdling on microbial N turnover. In both years of the experiment, we discovered (1) a summer N mineralization phase (between July and August) and (2) a winter N immobilization phase (November-February). The summer mineralization phase was characterized by a high N mineralization activity, low microbial N uptake, and a subsequent high N availability in the soil. During the autumn/winter N immobilization phase, gross N mineralization rates were low, and microbial N uptake exceeded microbial N mineralization, which led to high levels of N in the microbial biomass and low N availability in the soil. The observed immobilization phase during the winter may play a crucial role for ecosystem functioning, since it could protect dissolved N that is produced by autumn litter degradation from being lost from the ecosystem during the phase when plants are mostly inactive. The difference between microbial biomass N levels in winter and spring equals 38 kg N/ha and may thus account for almost one-third of the annual plant N demand. Tree girdling strongly affected annual N cycling: the winter N immobilization phase disappeared in girdled plots (microbial N uptake and microbial biomass N were significantly reduced, while the amount of available N in the soil solution was enhanced). This was correlated to a reduced fungal abundance in autumn in girdled plots. By releasing recently fixed photosynthates to the soil, plants may thus actively control the

  13. Effects of biomotor structures on performance of competitive gymnastics elements in elementary school male sixth-graders.

    Science.gov (United States)

    Delas, Suncica; Zagorac, Nebojsa; Katić, Ratko

    2008-06-01

    In order to identify the biomotor systems that determine performance of competitive gymnastics elements in elementary school male sixth-graders, factor structures of morphological characteristics and basic motor abilities were determined first, followed by relations of the morphological-motor system factors obtained with a set of criterion variables evaluating specific motor skills in competitive gymnastics in 110 male children aged 12 years +/- 3 months. Factor analysis of 17 morphological measures produced three morphological factors: factor of mesoectoendomorphy (general morphological factor) and factor of pronounced endomorphy, i.e. excessive adipose tissue, along with low skeleton longitudinality. Factor analysis of 16 motor variables yielded four motor factors: factor of general motoricity; factor integrating leg flexibility and arm explosiveness; factor juxtaposing body flexibility and repetitive leg strength; and factor predominantly defining leg movement frequency. Three significant canonical correlations, i.e. linear combinations, explained the association between the set of six latent variables of the morphological and basic motor system, and five variables assessing the knowledge in competitive gymnastics. The first canonical linear combination was based on the favorable and predominant impact of the general motor factor (a system integrating leg explosiveness, whole body coordination, relative arm and trunk strength, and arm movement frequency), along with unfavorable effect of morphological factors on the gymnastics elements performance, squat vault and handstand in particular The relation of the second pair of canonical factors pointed to the effects of leg flexibility and arm explosiveness on the cartwheel and backward pullover mount performance, whereas the relation of the third pair of canonical factors showed a favorable impact of the general morphological factor and leg movement frequency regulator on the forward shoulderkip from increase

  14. Arsenic(V) adsorption-desorption in agricultural and mine soils: Effects of organic matter addition and phosphate competition.

    Science.gov (United States)

    Arco-Lázaro, Elena; Agudo, Inés; Clemente, Rafael; Bernal, M Pilar

    2016-09-01

    High total and bioavailable concentrations of As in soils represent a potential risk for groundwater contamination and entry in the food chain. The use of organic amendments in the remediation of As-contaminated soils has been found to produce distinct effects on the solubility of As in the soil. Therefore, knowledge about As adsorption-desorption processes that govern its solubility in soil is of relevance in order to predict the behaviour of this element during these processes. In this paper, the objective was to determine As adsorption and desorption in four different soils, with and without compost addition, and also in competition with phosphate, through the determination of sorption isotherms. Batch experiments were carried out using three soils affected differently by previous mining activity of the Sierra Minera of La Unión-Cartagena (SE Spain) and an agricultural soil from Segovia province (central Spain). Adsorption was higher in the mining soils (and highest in the acidic one) than in the agricultural soils, although the latter were not affected negatively by organic matter or phosphate competition for sorption sites. The results show that As adsorption in most soils, both with and without compost, fitted better a multimolecular layer model (Freundlich), whereas As adsorption in competition with P fitted a monolayer model (Langmuir). Moreover, the use of compost and phosphate reduced the adsorption of As in the mining soils, while in the agricultural soils compost increased their low adsorption capacity. Therefore, the use of compost can be a good option to favour As immobilisation in soils of low adsorption, but knowledge of the soil composition will be crucial to predict the effects of organic amendments on As solubility in soils and its associated environmental risk.

  15. Effects of Generational Competition and Substitution on Late Labour Participation and Labour Market Exit from a Multilevel Perspective*

    Directory of Open Access Journals (Sweden)

    Dr. 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 infl uenced 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 infl uence individual participation and the transition to inactivity. To test these hypotheses, we use merged data from the fi rst 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 countryspecifi c factors and can quantify the relative impact of specifi c 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

  16. 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.

  17. Enzymatic degradation of plant cell wall polysaccharides: the kinetic effect of competitive adsorption

    DEFF Research Database (Denmark)

    Bergsøe, Merete Norsker; Bloch, Line; Adler-Nissen, Jens

    1999-01-01

    Insoluble potato dietary fibre, isolated from potato pulp, can be enzymatically hydrolysed with the pectolytic enzyme preparation Pectinex Ultra SP from Novo Nordisk A/S, in order to produce soluble fibre. The soluble fibre has valuable functional properties for the food industry. Cloned...... monocomponent enzymes from Pectinex Ultra SP (arabinofuranosidase, endoglucanase II, pectin lyase, polygalacturonase I, rhamnogalacturonan acetyl esterase, rhamnogalacturonase a, rhamnogalacturonase b and xylanase I) were added in order to increase the yield. Surprisingly, however, the yield is not increased...... when any of the monocomponent enzymes are added. To describe the results a new model designated 'the competitive activity adsorption model' is proposed. The model is based on the fact that the enzymes are adsorbed to the substrate before action. A combination of the Langmuir adsorption isotherm and...

  18. Effects of time delay on symmetric two-species competition subject to noise

    Science.gov (United States)

    Nie, Linru; Mei, Dongcheng

    2008-03-01

    Noise and time delay act simultaneously on real ecological systems. The Lotka-Volterra model of symmetric two-species competition with noise and time delay was investigated in this paper. By means of stochastic simulation, we find that (i) the time delay induces the densities of the two species to periodically oscillate synchronously; (ii) the stationary probability distribution function of the two-species densities exhibits a transition from multiple to single stability as the delay time increases; (iii) the characteristic correlation time for the sum of the two-species densities squared exhibits a nonmonotonic behavior as a function of delay time. Our results have the implication that the combination of noise and time delay could provide an efficient tool for understanding real ecological systems.

  19. Invasive plant suppresses the growth of native tree seedlings by disrupting belowground mutualisms.

    Directory of Open Access Journals (Sweden)

    Kristina A Stinson

    2006-05-01

    Full Text Available The impact of exotic species on native organisms is widely acknowledged, but poorly understood. Very few studies have empirically investigated how invading plants may alter delicate ecological interactions among resident species in the invaded range. We present novel evidence that antifungal phytochemistry of the invasive plant, Alliaria petiolata, a European invader of North American forests, suppresses native plant growth by disrupting mutualistic associations between native canopy tree seedlings and belowground arbuscular mycorrhizal fungi. Our results elucidate an indirect mechanism by which invasive plants can impact native flora, and may help explain how this plant successfully invades relatively undisturbed forest habitat.

  20. Development of allometric models for above and belowground biomass in swidden cultivation fallows of Northern Laos

    DEFF Research Database (Denmark)

    McNicol, Iain M.; Berry, Nicholas J.; Bruun, Thilde Bech;

    2015-01-01

    fields and patches of mature forest. Quantifying tree biomass in these landscapes is limited by the availability of reliable allometric models, hindering accurate carbon stock estimation and thus quantification of GHG emission associated with land use transitions. We therefore developed new allometric...... models for the prediction of both above- and below-ground woody biomass in swidden systems based on a destructive harvest of 150 trees in Luang Prabang Province, Laos People's Democratic Republic (PDR). This study is the first to develop allometric models of root biomass for swidden landscapes...

  1. 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...

  2. Children’s prosocial behavioural intentions toward outgroup members: The effects of intergroup competition, empathy and social perspective taking.

    OpenAIRE

    Abrams, Dominic; Pelletier, Joseph; Van de Vyer, Julie; Cameron, Lindsey; Lee, E

    2015-01-01

    When will children decide to help outgroup peers? We examined how intergroup competition, social perspective taking (SPT), and empathy influence children's (5–10 years, N = 287) prosocial intentions towards outgroup members. Study 1 showed that, in a minimal group situation, prosociality was lower in an intergroup competitive than in a non-competitive or interpersonal context. Study 2 revealed that, in a real groups situation involving intergroup competition, prosociality was associated with ...

  3. Modeling the competitive effect of ammonium oxidizers and heterotrophs on the degradation of MTBE in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A mathematical model was used to study effects on the degradation of methyl tert-butyl ether (MTBE) in a packed bed reactor due to the presence of contaminants such as ammonium, and the mix of benzene, toluene, ethylbenzene and xylenes (BTEX). It was shown that competition between the slower...... growing MTBE degraders and the co-contaminant oxidizers prevented MTBE's degradation when oxygen was limited. In this event, the co-contaminant oxidizers out-competed the MTBE degraders in the reactor's biofilm. However, if the oxygen supply was sufficient, MTBE would be fully degraded after the zone...... where the co-contaminants were oxidized. The results of the model further indicate that contradicting findings in the literature about the effects of BTEX on the degradation of MTBE are mainly due to differences in the study methodologies. Effects such as short-term toxicity of BTEX and the lack...

  4. Do plant traits predict the competitive abilities of closely related species?

    Science.gov (United States)

    Schwartz, Lauren M; Gibson, David J; Young, Bryan G

    2015-01-01

    Invasive species are a threat to every ecosystem. There is a strong incentive to predict which species will become invasive before they become too widespread and unmanageable. Different approaches have been advocated to assess invasive species potential. These include examining plant functional traits, quantifying competitive ability and phylogenetic comparison. In this study, we conducted experiments based on the above approaches in a multi-year, temporally replicated, set of experiments to compare these assessment methods to determine the invasive potential of Japanese chaff flower (Achyranthes japonica). We compared plant traits and competitive ability of Japanese chaff flower with two agricultural invasive species, Palmer amaranth (Amaranthus palmeri) and tall waterhemp (Amaranthus tuberculatus), and one endangered plant species, bloodleaf (Iresine rhizomatosa), in the Amaranthaceae. Additionally, we assessed the invasive potential based on each of these approaches and determined the degree of agreement between them. A relatively conservative assessment integrating all three approaches would be that the competitive ability of closely related individuals with similar functional traits would share invasive potential. In a greenhouse experiment, each of the study species and soya beans were grown as monocultures and were evaluated to assess the drawdown of an aboveground (light) and a belowground (nitrogen) resource. In a field experiment, each study species was grown at varying densities per 15-cm-diameter pot with or without one or two soya bean plants, to simulate relative densities for soya beans grown in 38- and 76-cm-wide row spacing, respectively. In addition, Japanese chaff flower seedlings were planted either as un-manipulated seedlings or as a seedling cut back to the soil surface at the four-node stage (cut Japanese chaff flower) at which point seedlings have reached a perennial growth stage. The greenhouse experiment showed that each species drew down

  5. Do plant traits predict the competitive abilities of closely related species?

    Science.gov (United States)

    Schwartz, Lauren M; Gibson, David J; Young, Bryan G

    2015-12-31

    Invasive species are a threat to every ecosystem. There is a strong incentive to predict which species will become invasive before they become too widespread and unmanageable. Different approaches have been advocated to assess invasive species potential. These include examining plant functional traits, quantifying competitive ability and phylogenetic comparison. In this study, we conducted experiments based on the above approaches in a multi-year, temporally replicated, set of experiments to compare these assessment methods to determine the invasive potential of Japanese chaff flower (Achyranthes japonica). We compared plant traits and competitive ability of Japanese chaff flower with two agricultural invasive species, Palmer amaranth (Amaranthus palmeri) and tall waterhemp (Amaranthus tuberculatus), and one endangered plant species, bloodleaf (Iresine rhizomatosa), in the Amaranthaceae. Additionally, we assessed the invasive potential based on each of these approaches and determined the degree of agreement between them. A relatively conservative assessment integrating all three approaches would be that the competitive ability of closely related individuals with similar functional traits would share invasive potential. In a greenhouse experiment, each of the study species and soya beans were grown as monocultures and were evaluated to assess the drawdown of an aboveground (light) and a belowground (nitrogen) resource. In a field experiment, each study species was grown at varying densities per 15-cm-diameter pot with or without one or two soya bean plants, to simulate relative densities for soya beans grown in 38- and 76-cm-wide row spacing, respectively. In addition, Japanese chaff flower seedlings were planted either as un-manipulated seedlings or as a seedling cut back to the soil surface at the four-node stage (cut Japanese chaff flower) at which point seedlings have reached a perennial growth stage. The greenhouse experiment showed that each species drew down

  6. Competition in the Cryptocurrency Market

    OpenAIRE

    Gandal, Neil; Hałaburda, Hanna

    2014-01-01

    We analyze how network effects affect competition in the nascent cryptocurrency market. We do so by examining the changes over time in exchange rate data among cryptocurrencies. Specifically, we look at two aspects: (1) competition among different currencies, and (2) competition among exchanges where those currencies are traded. Our data suggest that the winner-take-all effect is dominant early in the market. During this period, when Bitcoin becomes more valuable against the U.S. dollar, it a...

  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. Tax competition: A general review

    Directory of Open Access Journals (Sweden)

    Raičević Božidar B.

    2004-01-01

    Full Text Available Tax competition is increasingly attracting the attention of not only experts Although it is difficult to define precisely, grosso modo, it is actually a competition between states (jurisdictions in attracting capital (investors by tax instruments, especially tax incentives. The first recorded cases of tax competition emerged in 12th century (attracting wool weavers into regions of North Italy-Piemont. Today, tax competition has undreamt-of and very dynamic forms, both territorial and sectored. However, tax competition is accompanied not only by positive but also by rather strong negative effects. Positive effects worth mentioning are the following: 1. control of power, 2. innovations, and 3. incentives. However, negative effects, embodied in "unfair tax competition", provoke a range of unwanted and important distortions in international trade. All of them arise from requirements and wants of tax payers (especially companies to minimize or evade their tax obligations, on the one hand, as well as.

  9. Effect of temperature and cycle length on microbial competition in PHB-producing sequencing batch reactor.

    Science.gov (United States)

    Jiang, Yang; Marang, Leonie; Kleerebezem, Robbert; Muyzer, Gerard; van Loosdrecht, Mark C M

    2011-05-01

    The impact of temperature and cycle length on microbial competition between polyhydroxybutyrate (PHB)-producing populations enriched in feast-famine sequencing batch reactors (SBRs) was investigated at temperatures of 20 °C and 30 °C, and in a cycle length range of 1-18 h. In this study, the microbial community structure of the PHB-producing enrichments was found to be strongly dependent on temperature, but not on cycle length. Zoogloea and Plasticicumulans acidivorans dominated the SBRs operated at 20 °C and 30 °C, respectively. Both enrichments accumulated PHB more than 75% of cell dry weight. Short-term temperature change experiments revealed that P. acidivorans was more temperature sensitive as compared with Zoogloea. This is particularly true for the PHB degradation, resulting in incomplete PHB degradation in P. acidivorans at 20 °C. Incomplete PHB degradation limited biomass growth and allowed Zoogloea to outcompete P. acidivorans. The PHB content at the end of the feast phase correlated well with the cycle length at a constant solid retention time (SRT). These results suggest that to establish enrichment with the capacity to store a high fraction of PHB, the number of cycles per SRT should be minimized independent of the temperature.

  10. Soil abiotic factors influence interactions between belowground herbivores and plant roots.

    Science.gov (United States)

    Erb, Matthias; Lu, Jing

    2013-03-01

    Root herbivores are important ecosystem drivers and agricultural pests, and, possibly as a consequence, plants protect their roots using a variety of defensive strategies. One aspect that distinguishes belowground from aboveground plant-insect interactions is that roots are constantly exposed to a set of soil-specific abiotic factors. These factors can profoundly influence root resistance, and, consequently, the outcome of the interaction with belowground feeders. In this review, we synthesize the current literature on the impact of soil moisture, nutrients, and texture on root-herbivore interactions. We show that soil abiotic factors influence the interaction by modulating herbivore abundance and behaviour, root growth and resistance, beneficial microorganisms, as well as natural enemies of the herbivores. We suggest that abiotic heterogeneity may explain the high variability that is often encountered in root-herbivore systems. We also propose that under abiotic stress, the relative fitness value of the roots and the potential negative impact of herbivory increases, which may lead to a higher defensive investment and an increased recruitment of beneficial microorganisms by the plant. At the same time, both root-feeding herbivores and natural enemies are likely to decrease in abundance under extreme environmental conditions, leading to a context- and species-specific impact on plant fitness. Only by using tightly controlled experiments that include soil abiotic heterogeneity will it be possible to understand the impact of root feeders on an ecosystem scale and to develop predictive models for pest occurrence and impact.

  11. Belowground ectomycorrhizal fungal communities respond to liming in three southern Swedish coniferous forest stands

    DEFF Research Database (Denmark)

    Kjøller, Rasmus; Clemmensen, Karina

    2009-01-01

    In this study we report on changes in the belowground ectomycorrhizal fungal communities in southern Swedish coniferous forests as a consequence of liming with 3-7 ton limestone per hectare 16 years prior to the study. A total of 107 ectomycorrhizal fungi were identified from 969 independently sa...... community composition. We discuss the observed community changes in relation to ectomycorrhizal functionality and biodiversity in limed forests.......In this study we report on changes in the belowground ectomycorrhizal fungal communities in southern Swedish coniferous forests as a consequence of liming with 3-7 ton limestone per hectare 16 years prior to the study. A total of 107 ectomycorrhizal fungi were identified from 969 independently...... sampled root tips by sequencing the internal transcribed spacer region of the ribosomal DNA. Forty, 59 and 51 species were identified in three pine and spruce forests. Within all sites only about 25% of the species overlapped between the limed and the reference areas. However, the most abundant species...

  12. 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

    For implementation of simple yield loss models into threshold-based weed management systems, a thorough validation is needed over a great diversity of sites. Yield losses by competition wsth Sinapis alba L. (white mustard) as a model weed, were studied in 12 experiments in sugar beet (Beta vulgaris....... The results strongly suggest that the predictive ability of the leaf area model needs to be improved before it can be applied in weed management systems. Such improvement would require additional information about effects of abiotic factors on plant development and morphology and the definition of a time...... 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...

  13. Effect of solidification rate on competitive grain growth in directional solidification of a nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU YiZhou; SUN XiaoFeng

    2012-01-01

    The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science.Within the published research there exist conflicting views on the mechanism of grain overgrowth.To study the effect of solidification rate on grain structure evolution,bi-crystals samples were produced in a nickel-base superalloy at different solidification rates.It was found that at the convergent grain boundaries those grains better aligned with respect to the heat flux more readily overgrew neighbouring grains with misaligned orientations and the effect became more pronounced as solidification rate was increased.However,at diverging grain boundaries the rate of overgrowth was invariant to the solidification rate.These experimental results were compared with models in the literature.Thus,a better insight into competitive grain growth in directional solidification processes was obtained.

  14. Introduction of a 'carbon tax' and its effects on competitiveness in France and in Europe

    International Nuclear Information System (INIS)

    The implementation of a 'carbon tax' that is debated in France, following the Pigouvian principle of the 'polluter pays' and within a European framework, led us to examine more in depth the functioning of such a measure and the effects to foresee on French, and European, industrial competitiveness. While the controversy is focused on its apparent cost, we explain the virtuous spin-off effects and mechanisms of the internalisation of the carbon price by producers. The latter would indeed be incentivized to engage in an efficient substitution process across sources of energy and to intensify technological progress. Moreover, the 'double - even triple - dividend' of environmental taxation is a guarantee of the social acceptability of a tax that might be, in the long run, implemented under alternative forms. (author)

  15. 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.

  16. Controlling the redox reaction at the interface between sealing glasses and Cr-containing interconnect: Effect of competitive reaction

    Science.gov (United States)

    Chen, Shunrun; Lin, Jianxin; Yang, Hsiwen; Tang, Dian; Zhang, Teng

    2014-12-01

    In this paper, MnO2 is added to CaO-SrO-B2O3-SiO2 sealing system to control the redox glass/metal interfacial reaction in Solid Oxide Fuel Cells. The effect of MnO2 dopant on the valance states of Mn ions in glasses, the glass structure and glass/metal interfacial reaction is systematically investigated. The quenched glasses contain Mn2+ ion only; whereas, the Mn3+ content in glasses, held at 600 °C for 9 h, increases with increasing MnO2 dopant. The good bondage can be observed at the interfaces between Crofer 22APU and glass containing 6 mol % MnO2, held at 700 °C for 500 h. The competitive reaction reduces the redox chromate formation by consuming the oxygen at the glass/metal interface. In addition, the competitive reaction results in the formation of a continuous Mn-Cr oxide scale at the glass/metal interface, which is helpful for reducing the further diffusion of Cr from metallic interconnect to glass.

  17. Effects of plyometric training on endurance and explosive strength performance in competitive middle- and long-distance runners.

    Science.gov (United States)

    Ramírez-Campillo, Rodrigo; Alvarez, Cristian; Henríquez-Olguín, Carlos; Baez, Eduardo B; Martínez, Cristian; Andrade, David C; Izquierdo, Mikel

    2014-01-01

    The purpose of this study was to examine the effect of a short-term plyometric training program on explosive strength and endurance performance in highly competitive middle- and long-distance runners. Athletes were randomly assigned to a control group (CG, n = 18, 12 men) and an explosive strength training group (TG, n = 18, 10 men). Drop jump (DJ) from 20 (DJ20) and 40 cm (DJ40), countermovement jump with arms (CMJA), 20-m sprint time, and 2.4-km endurance run time test were carried out before and after 6 weeks of explosive strength training. Also, the combined standardized performance (CSP) in the endurance and explosive strength test was analyzed. After intervention, the CG did not show any significant change in performance, whereas the TG showed a significant reduction in 2.4-km endurance run time (-3.9%) and 20-m sprint time (-2.3%) and an increase in CMJA (+8.9%), DJ20 (+12.7%), and DJ40 (16.7%) explosive performance. Strength training group also exhibited a significant increase in CSP, although the CG showed significant reduction. We conclude that properly programmed concurrent explosive strength and endurance training could be advantageous for middle- and long-distance runners in their competitive performance, especially in events characterized by sprinting actions with small time differences at the end of the race. PMID:23838975

  18. Competitive Framing

    OpenAIRE

    Ran Spiegler

    2014-01-01

    I present a simple framework for modeling two-firm market competition when consumer choice is "frame-dependent", and firms use costless "marketing messages" to influence the consumer's frame. This framework embeds several recent models in the "behavioral industrial organization" literature. I identify a property that consumer choice may satisfy, which extends the concept of Weighted Regularity due to Piccione and Spiegler (2012), and provide a characterization of Nash equilibria under this pr...

  19. Effects of interspecific competition on the growth of macrophytes and nutrient removal in constructed wetlands: A comparative assessment of free water surface and horizontal subsurface flow systems.

    Science.gov (United States)

    Zheng, Yucong; Wang, Xiaochang; Dzakpasu, Mawuli; Zhao, Yaqian; Ngo, Huu Hao; Guo, Wenshan; Ge, Yuan; Xiong, Jiaqing

    2016-05-01

    The outcome of competition between adjoining interspecific colonies of Phragmites and Typha in two large field pilot-scale free water surface (FWS) and subsurface flow (SSF) CWs is evaluated. According to findings, the effect of interspecific competition was notable for Phragmites australis, whereby it showed the highest growth performance in both FWS and SSF wetland. In a mixed-culture, P. australis demonstrates superiority in terms of competitive interactions for space between plants. Furthermore, the interspecific competition among planted species seemed to cause different ecological responses of plant species in the two CWs. For example, while relatively high density and shoot height determined the high aboveground dry weight of P. australis in the FWS wetland, this association was not evident in the SSF. Additionally, while plants nutrients uptake accounts for a higher proportion of the nitrogen removal in FWS, that in the SSF accounts for a higher proportion of the phosphorous removal. PMID:26874442

  20. Effects of experience on the dimensions of intensity, direction and frequency of the competitive anxiety and self-confidence: A study in athletes of individual and team sports

    Directory of Open Access Journals (Sweden)

    Marcos Gimenes Fernandes

    2014-06-01

    Full Text Available The present study had the following objectives: i to examine the inter-scale correlations between the three dimensions of responses (intensity, direction and frequency of the CSAI-2R and its relationship with competitive experience, and ii evaluate the effect of competitive experience anxiety (cognitive and somatic and self-confidence in the total sample and for different types of modalities (individual vs. team. The sample consisted of 267 athletes (196 male and 71 female, of different sports, aged between 18 and 40 years (M = 24.30, SD = 5.62. Athletes completed the Brazilian version of the CSAI-2, which included the addition of the dimensions of direction and frequency response. Spearman test and Manova were used for the data analysis. Overall, it was found that the competitive experience has a high multivariate and significant effect on the dimensions of competitive anxiety. Both individual and team athletes with low competitive experience showed a trend to report lower levels of self-confidence intensity, compared to counterparts with high competitive experience. These results were discussed in view of the theoretic framework and practical implications planning Sport Psychology intervention programs in local athletes with different backgrounds.

  1. Competition Fosters Trust

    DEFF Research Database (Denmark)

    Huck, Steffen; Ruchala, Gabriele K.; Tyran, Jean-Robert

    We study the effects of reputation and competition in a stylized market for experience goods. If interaction is anonymous, such markets perform poorly: sellers are not trustworthy, and buyers do not trust sellers. If sellers are identifiable and can, hence, build a reputation, efficiency quadruples...... but is still at only a third of the first best. Adding more information by granting buyers access to all sellers’ complete history has, somewhat surprisingly, no effect. On the other hand, we find that competition, coupled with some minimal information, eliminates the trust problem almost completely...

  2. Competition Fosters Trust

    DEFF Research Database (Denmark)

    Huck, Steffen; Lünser, Gabriele; Tyran, Jean-Robert Karl

    2012-01-01

    We study the effects of reputation and competition in a trust game. If trustees are anonymous, outcomes are poor: trustees are not trustworthy, and trustors do not trust. If trustees are identifiable and can, hence, build a reputation, efficiency quadruples but is still at only a third of the first...... best. Adding more information by granting trustors access to all trustees' complete history has, somewhat surprisingly, no effect. On the other hand, we find that competition, coupled with some minimal information, eliminates the trust problem almost completely...

  3. Effects of competitive and noncompetitive 5α-reductase inhibitors on serum and intra-prostatic androgens in beagle dogs

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-feng; YANG Yong; WANG Wei; QIU Zhi; ZHANG Peng; WANG Biao

    2013-01-01

    Background 5α-Reductase inhibitors (5α-RI) act by inhibiting the conversion of testosterone to dihydrotestosterone (DHT),thereby preventing DHT induced benign prostatic hyperplasia.The existing 5α-RIs can be classified into two types:competitive and noncompetitive.Currently,limited evidence is available concerning the effect differences between the two types of 5α-RI on androgens.The purpose of this study was to assess the effects of competitive and noncompetitive 5α-RIs on serum and intra-prostatic androgens in beagle dogs.Methods Twenty beagles with spontaneous benign prostatic hyperplasia were randomly allocated into two groups:epristeride group (n=10) in which beagles were treated with epristeride at 1 mg/kg once a day for 3 months,and finasteride group (n=10) in which beagles were treated with finasteride at 1 mg/kg once a day for 3 months.The levels of intra-prostatic testosterone and DHT were measured before treatment and on day one after three months medication.Serum levels of testosterone and DHT were measured at the same time points.Changes in androgen levels before and after treatment were analyzed,and comparisons were made within each treatment group and between treatment groups.Results After 3-month treatment,serum and intra-prostatic DHT levels all decreased significantly in both the epristeride and finasteride groups.The change of DHT in serum was significantly higher in the finasteride group (-14% and-43% in epristeride and finasteride groups respectively,with P<0.001); however there was no significant difference in the changes of intra-prostatic DHT between the two groups (-47% and-51% in epristeride and finasteride groups,respectively,P=0.304).The decreases in DHT levels were accompanied by reciprocal increases in serum and intra-prostatic testosterone levels.Changes of testosterone were significantly higher in finasteride group both in serum (20% and 42%in epristeride and finasteride groups,respectively,P<0.001) and in

  4. Do elevations in temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated silver birch seedlings?

    Science.gov (United States)

    Huttunen, Liisa; Saravesi, Karita; Markkola, Annamari; Niemelä, Pekka

    2013-09-01

    Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.

  5. The effect of group composition and age on social behaviour and competition in groups of weaned dairy calves

    DEFF Research Database (Denmark)

    Færevik, G.; Jensen, Margit Bak; Bøe, K. E.

    2010-01-01

    The objective of the present study was to investigate how group composition affects behavior and weight gain of newly weaned dairy calves and how age within heterogeneous groups affects behavior and competition. Seventy-two calves were introduced into 6 groups of 12 calves, of which 3 groups were...... homogeneous and 3 groups were heterogeneous (including 6 young and 6 old calves). The 9.8 m × 9.5 m large experimental pen had 4 separate lying areas as well as a feeding area. Behavior and subgrouping were recorded on d 1, 7, and 14 after grouping, and calves were weighed before and after the experimental...... period of 14 d. Analysis of the effect of group composition on behavior and weight gain included young calves in heterogeneous groups and calves in homogeneous groups within the same age range at grouping (30 to 42 d). Irrespective of group composition, time spent feeding and lying increased, whereas...

  6. Effective Psychology Training on Competition%赛前心理训练对比赛的影响

    Institute of Scientific and Technical Information of China (English)

    刘成艳

    2011-01-01

    In the modern competitive sport,winning the key psychological factors become an important part of mental training of athletes and coaches also been much concern of researchers.Use of effective psychological training methods,can overcome the psychological%在现代竞技体育比赛中,心理因素成为胜负关键的一个重要环节,运动员的心理训练也就一直备受教练员和科研人员的关注。采用有效的心理训练方法,可以克服临场发挥的心理障碍,使运动员具有良好的比赛状态,有利于提高比赛成绩。

  7. Effectiveness of competitive activity of high class hockey players accounting a level of their self-esteem

    Directory of Open Access Journals (Sweden)

    Mikhnov A.P.

    2015-02-01

    Full Text Available Purpose : study the effect of increasing the level of self-esteem on the efficiency of competitive activity of high class players. Material : the study involved sixteen athletes (Atlanta, Moscow region. - Continental Hockey League. Results : it was found that the application of special training self-esteem increases the level of implementation of technical and tactical action games. Number of goals increased by 8.92%, assists - 21.5%, the total number of shots on goal - to 20.02%. Conclusions : it is recommended specialized program correction level of self-esteem from 10 separate studies. Classes have different target setting: habit forming positive attitudes towards themselves, develop skills of active life position, securing high self-esteem. The program is used for two weeks in the preparatory period of training.

  8. The effect of UV-B radiation enhancement on the interspecific competition between Skeletonema costatum and Heterosigma akashiwo

    Institute of Scientific and Technical Information of China (English)

    XIAO Hui; TANG Xuexi; ZHANG Peiyu; CAI Hengjiang

    2005-01-01

    The responses of the interspecific competition between Skeletonema costatum and Heterosigma akashiwo to UV-B radiation enhancement were studied by the co-culture method. The results showed that Heterosigma akashiwo exhibited inhibition on the growth of Skeletonema costatum, and with the increase of initial inoculation density of Heterosigma akashiwo, heavier inhibition on Skeletonema costatum appeared. Under different inoculation proportions, Heterosigma akashiwo could always be in predominance in competition with Skeletonema costatum. The UV-B radiation treatment could change the competition relationship between Skeletonema costatum and Heterosigma akashiwo, which could increase the competitive dominance of Skeletonema costatum and decrease the competitive dominance of Heterosigma akashiwo. When the inoculation proportions of Heterosigma akashiwo and Skeletonema costatum were H:S=1:4 and H:S=1:1, Skeletonema costatum was in predominance in this competition; however, Heterosigma akashiwo was in predominance when the inoculation proportion was H:S=4:1.

  9. Herbivory and Competition of Tibetan Steppe Vegetation in Winter Pasture: Effects of Livestock Exclosure and Plateau Pika Reduction.

    Directory of Open Access Journals (Sweden)

    Richard B Harris

    Full Text Available Rangeland degradation has been identified as a serious concern in alpine regions of western China on the Qinghai-Tibetan plateau (QTP. Numerous government-sponsored programs have been initiated, including many that feature long-term grazing prohibitions and some that call for eliminating pastoralism altogether. As well, government programs have long favored eliminating plateau pikas (Ochotona curzoniae, assumed to contribute to degraded conditions. However, vegetation on the QTP evolved in the presence of herbivory, suggesting that deleterious effects from grazing are, to some extent, compensated for by reduced plant-plant competition. We examined the dynamics of common steppe ecosystem species as well as physical indicators of rangeland stress by excluding livestock and reducing pika abundance on experimental plots, and following responses for 4 years. We established 12 fenced livestock exclosures within pastures grazed during winter by local pastoralists, and removed pikas on half of these. We established paired, permanent vegetation plots within and outside exclosures and measured indices of erosion and biomass of common plant species. We observed modest restoration of physical site conditions (reduced bare soil, erosion, greater vegetation cover with both livestock exclusion and pika reduction. As expected in areas protected from grazing, we observed a reduction in annual productivity of plant species avoided by livestock and assumed to compete poorly when protected from grazing. Contrary to expectation, we observed similar reductions in annual productivity among palatable, perennial graminoids under livestock exclusion. The dominant grass, Stipa purpurea, displayed evidence of density-dependent growth, suggesting that intra-specific competition exerted a regulatory effect on annual production in the absence of grazing. Complete grazing bans on winter pastures in steppe habitats on the QTP may assist in the recovery of highly eroded pastures

  10. Effect of naloxone on food competition aggression in food-restricted high and low aggression pigeons (Columba livia

    Directory of Open Access Journals (Sweden)

    Fachinelli C.

    2004-01-01

    Full Text Available We determined the effect of the opiate receptor antagonist naloxone on aggression, emotion, feeder control, and eating behavior in high and low aggression female pigeons maintained at 80% of their normal weight and exposed to food competition interactions. Pigeons were divided into pairs by previously ranked high aggression (total time spent in offensive aggression exceeding 60 s/5 min; N = 6 pairs and low aggression females (time spent in offensive aggression less than 10 s/5 min; N = 6 pairs. A pigeon in each pair received an sc dose of naloxone (1 mg kg-1 ml saline-1 and the other animal received the vehicle. Trials (10 min were performed 30 min after the naloxone/vehicle administration. The naloxone group of high aggression pigeons showed lower scores of total time spent in offensive aggression (control: 98.6 ± 12.0; naloxone: 46.8 ± 6.6 s; P < 0.05 and higher scores of time spent in emotional responses (control: 3.5 ± 0.6; naloxone: 10.8 ± 2.4 s; P < 0.05 than controls. The other behaviors scored, feeder control and eating behavior, were not affected in this group. The naloxone group of low aggression pigeons, however, showed higher scores of offensive aggression than their controls (5.3 ± 1.3; naloxone: 28.7 ± 8.0 s; P < 0.05. The present results suggest that opiate receptor mechanisms are implicated in offensive aggression responses in high and low aggression pigeons. However, as reported for brain 5-hydroxytryptamine manipulation and GABA-A-benzodiazepine receptor manipulation, the effect of the opiate receptor antagonist on food competition aggression in pigeons was related to their pretreatment level of aggression.

  11. THE EFFECT OF STRUCTURAL FUNDS ON REGIONAL COMPETITIVENESS IN THE NEW EU COUNTRIES: THE CASE OF ROMANIA AND BULGARIA

    Directory of Open Access Journals (Sweden)

    GLIGOR DELIA ANCA GABRIELA

    2015-03-01

    Full Text Available In the context of internationalization and globalization of the world economy, regional competitiveness is thoroughly debated by politicians and policy makers, emphasizing measurable differences between development regions, without any clear political or conceptual framework. The process of European Union integration is a main driving force of change, aiming to increase the efficiency and competitiveness of the fragmented European economy in the face of increasing internationalization. This often exposes countries and regions with unequal resources and technology and different economic structures to international competition. Such is the case of Romania and Bulgaria, countries that after joining the European Union in 2007 were given an opportunity to recover in terms of regional competitiveness and economic growth, namely structural funds as a form of nonrefundable European financial help to disadvantaged regions of member states. This research is thus focused on underlining and analyzing the relation between structural funds’ absorption and the degree of regional competitiveness for the development regions of Romania and Bulgaria, during their first programming period, through identifying and analyzing the factors that influence regional competitiveness and the amount of structural funds absorbed. First, two competitiveness country profiles are created based on data provided by relevant international organisms and second, an impact analysis is developed using six regional competitiveness indicators, grouped into three categories (economic, social and technological. Results show that EU funds critically influence the competitiveness of Romanian and Bulgarian regions, providing reliable data for policy decision makers

  12. Do Loyalty Programs Enhance Behavioral Loyalty: An Empirical Analysis Accounting for Program Design and Competitive Effects

    OpenAIRE

    Leenheer, J.; Bijmolt, T.H.A.; Heerde, H.J. van; Smidts, A.

    2002-01-01

    This paper studies the effects of loyalty programs on share-of-wallet using market-wide household panel data on supermarket purchases.We find that loyalty programs relate positively to share-of-wallet, but the programs differ in effectiveness and some are ineffective.Both a saving component and a multi-vendor structure enhance the effectiveness of a loyalty program, but high discounts do not lead to higher share-of-wallets.Further, if households have multiple loyalty cards, the effectiveness ...

  13. Do Loyalty Programs Enhance Behavioral Loyalty : An Empirical Analysis Accounting for Program Design and Competitive Effects

    NARCIS (Netherlands)

    Leenheer, J.; Bijmolt, T.H.A.; van Heerde, H.J.; Smidts, A.

    2002-01-01

    This paper studies the effects of loyalty programs on share-of-wallet using market-wide household panel data on supermarket purchases.We find that loyalty programs relate positively to share-of-wallet, but the programs differ in effectiveness and some are ineffective.Both a saving component and a mu

  14. 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 o...

  15. Competitive reaction- and feedback effects based on VARX models of pooled store data

    NARCIS (Netherlands)

    Horvath, C; Leeflang, PSH; Wieringa, JE; Wittink, DR

    2005-01-01

    We apply a model that accommodates dynamic phenomena in demand- and reaction functions. The latter functions capture reactions to actions as well as to consequences of actions. We estimate a fixed effects VARX model with dynamic and interactive effects for multiple brands based on pooled time series

  16. The future of competitions

    DEFF Research Database (Denmark)

    Bates, Gary; Jensen, Boris Brorman; Miessen, Markus

    2010-01-01

    We wanted to explore the potential of the competition. The question we asked ourselves was if the competition can generate new, relevant and critical ideas within architecture? We organized an idea competition about the architectural competition.......We wanted to explore the potential of the competition. The question we asked ourselves was if the competition can generate new, relevant and critical ideas within architecture? We organized an idea competition about the architectural competition....

  17. Competition between electronic Kerr and free carrier effects in an ultimate-fast optically switched semiconductor microcavity

    CERN Document Server

    Yüce, E; Claudon, J; Dupuy, E; Boller, K J; Gérard, J M; Vos, W L

    2012-01-01

    We have performed ultrafast pump-probe experiments on a GaAs-AlAs microcavity with a resonance near 1300 nm in the "original" telecom band. We concentrate on ultimate-fast optical switching of the cavity resonance that is measured as a function of pump-pulse energy. We observe that at low pump-pulse energies the switching of the cavity resonance is governed by the instantaneous electronic Kerr effect and is achieved within 300 fs. At high pump-pulse energies the index change induced by free carriers generated in the GaAs start to compete with the electronic Kerr effect and reduce the resonance frequency shift. We have developed an analytic model which predicts this competition in agreement with the experimental data. Our model includes a new term in the intensity-dependent refractive index that considers the effect of the probe pulse intensity, which is resonantly enhanced by the cavity. We calculate the effect of the resonantly enhanced probe light on the refractive index change induced by the electronic Ker...

  18. Crop–weed competition

    DEFF Research Database (Denmark)

    Gallandt, Eric R.; Weiner, Jacob

    2015-01-01

    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...... 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...... on crops. Longer term management of crop–weed competition can be achieved through crop rotations, specifically crop sequences that reduce the weed seed bank, and therefore seedling density, and prevent proliferation of perennial weeds. Key ConceptsKey Concepts * Plant growth requires sunlight, water...

  19. The power of competition

    International Nuclear Information System (INIS)

    The change-over from regulated monopolies to a non-regulated competitive market in the electric utility industry was discussed in terms of marketing and survival strategies for utilities it the newly competitive marketplace. The impact of low natural gas prices was prominently discussed as a danger to hydroelectricity generators because high efficiency turbine generators that are now available. Surplus power capacity in both the Canadian and US markets were discussed. The effects of independent power producers selling electricity wholesale to private utilities was also debated on account of its potential to change the role of the electric utility. The situation of the Bonneville Power Association (BPA), a self-financed government agency, as owner of 15 000 miles of transmission grid that is not allowed to own generation plants, was described. Strategies developed by BPA in an effort to adapt to the competitive market were described and were successful

  20. IMPACT OF AMT INVESTMENTS ON EFFECTIVENESS AND COMPETITIVENESS OF MANUFACTURING SYSTEMS

    OpenAIRE

    Miroslav Chodur; Premysl Palka

    2009-01-01

    Every manufacturing company is a system of individual manufacturing units, which have to be carefully laid out taking into account time, space, technology, and organisation perspective in order to deliver maximum final product. In order to secure absolute effective and efficient functionality of manufacturing process all manufacturing units have to be reviewed already in stage of its planning and organising. Only continual process of measuring, evaluating and managing effectiveness of individ...