Competitive Performance (competitive + performance)

Distribution by Scientific Domains


Selected Abstracts


Active target particle swarm optimization

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 1 2008
Ying-Nan Zhang
Abstract We propose an active target particle swarm optimization (APSO). APSO uses a new three-target velocity updating formula, i.e. the best previous position, the global best position and a new target position (called active target). In this study, we distinguish APSO from EPSO (extended PSO)/PSOPC (PSO with passive congregation) by the different methods of getting the active target. Note that here EPSO and PSOPC are the two existing methods for using three-target velocity updating formula, and getting the third (active) target from the obtained positions by the swarm. The proposed APSO gets the active (third) target using complex method, where the active target does not belong to the existing positions. We find that the APSO has the advantages of jumping out of the local optimum and keeping diversity; however, it also has the disadvantages of adding some extra computation expenses. The experimental results show the competitive performance of APSO when compared with PSO, EPSO, and PSOPC. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Performance comparison of MPI and OpenMP on shared memory multiprocessors

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 1 2006
Géraud Krawezik
Abstract When using a shared memory multiprocessor, the programmer faces the issue of selecting the portable programming model which will provide the best performance. Even if they restricts their choice to the standard programming environments (MPI and OpenMP), they have to select a programming approach among MPI and the variety of OpenMP programming styles. To help the programmer in their decision, we compare MPI with three OpenMP programming styles (loop level, loop level with large parallel sections, SPMD) using a subset of the NAS benchmark (CG, MG, FT, LU), two dataset sizes (A and B), and two shared memory multiprocessors (IBM SP3 NightHawk II, SGI Origin 3800). We have developed the first SPMD OpenMP version of the NAS benchmark and gathered other OpenMP versions from independent sources (PBN, SDSC and RWCP). Experimental results demonstrate that OpenMP provides competitive performance compared with MPI for a large set of experimental conditions. Not surprisingly, the two best OpenMP versions are those requiring the strongest programming effort. MPI still provides the best performance under some conditions. We present breakdowns of the execution times and measurements of hardware performance counters to explain the performance differences. Copyright © 2005 John Wiley & Sons, Ltd. [source]


ECOLOGICAL BISTABILITY AND EVOLUTIONARY REVERSALS UNDER ASYMMETRICAL COMPETITION

EVOLUTION, Issue 6 2002
Fabio Dercole
Abstract How does the process of life-history evolution interplay with population dynamics? Almost all models that have addressed this question assume that any combination of phenotypic traits uniquely determine the ecological population state. Here we show that if multiple ecological equilibria can exist, the evolution of a trait that relates to competitive performance can undergo adaptive reversals that drive cyclic alternation between population equilibria. The occurrence of evolutionary reversals requires neither environmentally driven changes in selective forces nor the coevolution of interactions with other species. The mechanism inducing evolutionary reversals is twofold. First, there exist phenotypes near which mutants can invade and yet fail to become fixed; although these mutants are eventually eliminated, their transitory growth causes the resident population to switch to an alternative ecological equilibrium. Second, asymmetrical competition causes the direction of selection to revert between high and low density. When ecological conditions for evolutionary reversals are not satisfied, the population evolves toward a steady state of either low or high abundance, depending on the degree of competitive asymmetry and environmental parameters. A sharp evolutionary transition between evolutionary stasis and evolutionary reversals and cycling can occur in response to a smooth change in ecological parameters, and this may have implications for our understanding of size-abundance patterns. [source]


Evaluating human capital: an exploratory study of management practice

HUMAN RESOURCE MANAGEMENT JOURNAL, Issue 4 2004
Juanita Elias
The article explores the development of systems of human capital evaluation in a number of large UK firms. Human capital is a much used term in business literature, and it is widely recognised that firms need to develop mechanisms to determine the value of their employee base. An extensive human capital literature has developed in which the authors propose elaborate systems for measuring a firm's human assets. This article does not seek to offer yet another human capital model. Rather, the aim is to examine the management practices through which human capital evaluation is undertaken. The article is based on an exploratory study of such practices in 11 major firms in the UK. The findings are highlighted as follows. First, we note the preference for internal over external (static accountancy-based) reporting. Secondly, we highlight the diverse nature of human capital evaluation systems that exist across UK business. Thirdly, we explore the relationship between practices of evaluation and the role and position of the HR function within the firm. Finally, in conclusion, we address the implications of the human capital perspective for practitioners, arguing that there is no single formula that can be applied to its evaluation. We go on to suggest that the importance of the human capital concept and its measurement may lie in its ability to re-frame perceptions of the relationship between the contribution of employees and the competitive performance of the business. [source]


Radiofrequency Catheter Ablation of Atrial Fibrillation in Athletes Referred for Disabling Symptoms Preventing Usual Training Schedule and Sport Competition

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2008
FRANCESCO FURLANELLO M.D.
Introduction: Atrial fibrillation (AF) may occasionally affect athletes by impairing their ability to compete, and leading to noneligibility at prequalification screening. The impact of catheter ablation (CA) in restoring full competitive activity of athletes affected by AF is not known. The aim of our study was to investigate the effectiveness of CA of idiopathic AF in athletes with palpitations impairing physical performance and compromising eligibility for competitive activities. Methods and Results: Twenty consecutive competitive athletes (all males; 44.4 ± 13.0 years) with disabling palpitations on the basis of idiopathic drug-refractory AF underwent 46 procedures (2.3 ± 0.4 per patient) according to a prospectively designed multiprocedural CA approach that consolidates pulmonary veins (PV) isolation through subsequent steps. Preablation, effort-induced AF could be documented in 13 patients (65%) during stress ECG and significantly reduced maximal effort capacity (176 ± 21 W), as compared with patients with no AF during effort (207 ± 43 W, P < 0.05). At the end of CA protocol, which also included ablation of atrial flutter (AFL) in 7 patients, 18 (90.0%) patients were free of AF and two (10.0%) reported short-lasting (minutes) episodes of palpitations during 36.1 ± 12.7 months follow-up. Compared with preablation, postablation maximal exercise capacity significantly improved (from 183 ± 32 to 218 ± 20 W, P < 0.02). All baseline quality of life (QoL) parameters pertinent to physical activity significantly improved (P < 0.05) at the end of CA protocol. All athletes obtained reeligibility and could effectively reinitiate sport activity. Conclusions: AF, alone or in combination with AFL, may significantly impair maximal effort capacity thereby limiting competitive performance. Multiple PV isolation proved very effective in these patients to restore full competitive activity and allow reeligibility. [source]


Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2004
S. Puustinen
Abstract Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infections with nonrelated parasites. This result agrees with the predictions of theories on the evolution of parasite virulence: to enhance parasite transmission, selection may favour reduced competition with genetically related parasites in hosts infected by several genotypes. However, in contrast to the most common predictions, nonrelated infections were not more virulent than the sibling infections. [source]


A CONCEPTUAL UNDERSTANDING OF REQUIREMENTS FOR THEORY-BUILDING RESEARCH: GUIDELINES FOR SCIENTIFIC THEORY BUILDING,

JOURNAL OF SUPPLY CHAIN MANAGEMENT, Issue 3 2008
JOHN G. WACKER
Business academics have focused their attention on empirical investigation of programs' effect on organizational competitive performance. These studies primarily emphasize theory building. With the many definitions of theory, academics are not certain whether their research papers meet the specific requirements for theory development required by the academic field of the philosophy of science. Certainly, supply chain academics generally believe that their academic articles fulfill the requirements of theory building. Although many of these articles do have elements of theory, more focus is needed on the specific requirements of theory to assure that academic research is "good" theory building. The primary purpose of this research paper is to logically develop a set of guidelines to assist empirical researchers to assure that their studies fulfill the requirements of good theory based upon traditional scientific theory building. By fulfilling the requirements of good theory, researchers will develop studies that will have a lasting impact on their academic field. To achieve a lasting impact on an academic field, it is necessary to follow a logical plan. This article provides a plan for logical guidelines for developing an understanding of how and why "good" theory building is achieved. This article logically develops a formal conceptual definition of theory along with its related properties to understand these guidelines. Next, it analyzes the requirements of theory, "good" theory, and their properties. These guidelines are included in the existing philosophy of science publications. However, this article consolidates these sources and logically explains why these guidelines are needed. In the conclusion, the guidelines are summarized to serve as a summary checklist for supply chain researchers to use for ensuring their articles will be recognized as a contribution to the academic field. So in that sense, this article does not develop a revolutionary new insight into theory-building empirical articles, but rather integrates diverse traditional philosophy of science requirements into a much simpler set of guidelines. Through logical development of these guidelines, researchers will understand the structure of theory and how to ensure their studies can be modified to have a lasting impact on the field of supply chain management. [source]


Relative competitive performance of 63 species of terrestrial herbaceous plants

JOURNAL OF VEGETATION SCIENCE, Issue 1 2002
P. Keddy
Gleason & Cronquist (1963); Morton & Venn (1990) Abstract. There is growing evidence that plant and animal species are arranged in hierarchies of relative competitive performance. More work is needed to determine which plant traits best predict relative competitive performance. We therefore measured relative competitive performance of 63 terrestrial herbaceous plant species using Trichostema brachiatum as a reference species (that is, phytometer or target species). The neighbour species came from a wide array of terrestrial vegetation types (e.g. rock barrens, alvars, old fields), and represented a wide array of growth forms (e.g. small rosette species such as Saxifraga virginiensis and large clonal graminoids such as Agropyron repens). The experiment was repeated with two pot sizes: large (control) and small (stress treatment). Relative competitive performance in large pots (controls) was highly correlated with that in small pots (stress treatment) (r = 0.90, p < 0.001). The hierarchy of relative competitive performance in the large pots was also highly correlated with the hierarchy in the small (stressed) pots (rs = 0.91, p < 0.001). Principal components analysis and multiple linear regression showed that plant size (measured by total biomass, above-ground biomass, below-ground biomass, canopy area, height and leaf area index) and leaf shape (measured as length to width ratio, length, width) were the two characteristics that best predicted relative competitive performance (large pots, r2 = 0.55; small pots, r2 = 0.48). [source]


Quality Concepts for the Improved Use of Recycled Polymeric Materials: A Review

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2008
Francisco Vilaplana
Abstract Polymeric waste materials should be considered resources for the manufacture of new products through recycling processes, with a similar status to virgin fossil-based plastics and biopolymers from renewable resources. Several efforts can be made to achieve this qualitative quantum leap in plastics recycling, and consequently introduce recycled products, with competitive performance, to the market. Scientific knowledge about the degradation processes during the life cycle and the development of fast and reliable analytical methods for the quality assessment of recycled plastics are fundamental to guarantee their performance in new applications. Different strategies,restabilisation, rebuilding, compatibilisation, and addition of elastomers and fillers,can be used to upgrade the structure and properties of polymeric waste streams. This review discusses recent developments in the mechanical recycling of plastics, focusing on how to produce quality materials from waste streams and, thus, contribute to a sustainable management of resources and energy. [source]


Picking battles wisely: plant behaviour under competition

PLANT CELL & ENVIRONMENT, Issue 6 2009
ARIEL NOVOPLANSKY
ABSTRACT Plants are limited in their ability to choose their neighbours, but they are able to orchestrate a wide spectrum of rational competitive behaviours that increase their prospects to prevail under various ecological settings. Through the perception of neighbours, plants are able to anticipate probable competitive interactions and modify their competitive behaviours to maximize their long-term gains. Specifically, plants can minimize competitive encounters by avoiding their neighbours; maximize their competitive effects by aggressively confronting their neighbours; or tolerate the competitive effects of their neighbours. However, the adaptive values of these non-mutually exclusive options are expected to depend strongly on the plants' evolutionary background and to change dynamically according to their past development, and relative sizes and vigour. Additionally, the magnitude of competitive responsiveness is expected to be positively correlated with the reliability of the environmental information regarding the expected competitive interactions and the expected time left for further plastic modifications. Concurrent competition over external and internal resources and morphogenetic signals may enable some plants to increase their efficiency and external competitive performance by discriminately allocating limited resources to their more promising organs at the expense of failing or less successful organs. [source]


Assessing the dominance of Phleum pratense cv. climax, a species commonly used for ski trail restoration

APPLIED VEGETATION SCIENCE, Issue 2 2009
Francis Isselin-Nondedeu
Abstract Questions: (1) Are some species used for ski trail restoration too dominant to allow native species to re-establish? (2) What plant traits can be used to predict which species are good competitors? We tested the hypothesis that limited native species establishment on ski trails is caused by (1) the dominance of Phleum pratense cv. climax (PPC) and (2) the asymmetry of competitive interactions. Location: Sub-alpine area in the northern French Alps. Methods: PPC was cultivated outdoors over 2 years with 15 alpine species in a systematic design with high- and low-nutrient soil conditions. For each species relative survival, competitive performance and relationships with plant traits were measured. Results: PPC exerted strong dominance on most of its neighbouring species. Survival performance of Anthyllis vulneraria, Luzula sudetica and Lotus alpinus were dramatically reduced. Results of above-ground competition showed that species were trapped in asymmetric competition. Festuca rubra, Trifolium repens, Alchemilla xanthochlora, Trifolium pratense and Plantago alpina best counteracted PPC. Below-ground competition was more symmetric, particularly at the high nutrient level. Plant traits such as biomass, canopy size and specific leaf area were positively correlated with competitive performance of the species. Conclusion: The study has implications for the management of restored ski trails since PPC may hinder the establishment of native sub-alpine species. Consequently, recommendations should focus on (1) maintaining a low proportion or decreasing the proportion of PPC seeds in the revegetation mix and (2) reducing soil fertilization. Plant traits and competition experiments can help to predict changes in restored grasslands. [source]


On not wanting it to count: reading together as resistance1

AREA, Issue 1 2009
Bonnie Kaserman
Reading groups can be spaces of resistance, both from the competitive performances of some classroom seminars and from the calculative fields of neoliberalizing departments and universities. As graduate students, we offer this intervention as a consideration of the bodily politics of academic reproductions. In discussing the embodiment of textual practices in seminar and in reading groups, we point to monologue, ,trashing' criticism, and obscurity as practices habituated in the classroom seminar. We discuss how reading groups contest ,proper' knowledges, while enabling a multiplicity of textual, bodily practices. Finally, we consider how certain reading practices potentially de-stabilise neo-liberal subject formation in the academy. We discuss why we do not want reading groups to count, as a strategy for resisting accounting and accountable regimes in our departments and universities. [source]