Search results for "competition."
showing 10 items of 1367 documents
Pseudo-Cut Strategies for Global Optimization
2011
Motivated by the successful use of a pseudo-cut strategy within the setting of constrained nonlinear and nonconvex optimization in Lasdon et al. (2010), we propose a framework for general pseudo-cut strategies in global optimization that provides a broader and more comprehensive range of methods. The fundamental idea is to introduce linear cutting planes that provide temporary, possibly invalid, restrictions on the space of feasible solutions, as proposed in the setting of the tabu search metaheuristic in Glover (1989), in order to guide a solution process toward a global optimum, where the cutting planes can be discarded and replaced by others as the process continues. These strategies can…
INTRA- AND INTERSPECIFIC VARIATION IN INTERNAL STRUCTURES OF THE GENUSSTENOSARINA(BRACHIOPODA, TEREBRATULIDA) USING LANDMARKS
2001
Abstract Although a number of brachiopod genera have been defined mainly from their internal structures, the fixity of those structures has rarely been investigated. Variability of the rather simple loops of two New Caledonian species of the Recent genus Stenosarina (Terebratulida), one species having a variant with endemic morphology, provides insight into the relationship between the two species. Procrustes methods based on landmarks are used. Intra-population variability is found to be of the same order of magnitude as inter-population variability. Moreover, the morphological distance between the endemic variant and the other specimens is greater than the distance between the two species…
Modelling Bacterial Dynamics in Food Products: Role of Environmental Noise and Interspecific Competition
2013
In this paper we review some results obtained within the context of the predictive microbiology, which is a specific field of the population dynamics. In particular we discuss three models, which exploit tools of statistical mechanics, for bacterial dynamics in food of animal origin. In the first model, the random fluctuating behaviour, experimentally measured, of the temperature is considered. In the second model stochastic differential equations are introduced to take into account the influence of physical and chemical variables, such as temperature, pH and activity water, subject to deterministic and random variations. The third model, which is an extended version of the second one, negl…
A stochastic interspecific competition model to predict the behaviour of Listeria monocytogenes in the fermentation process of a traditional Sicilian…
2008
The present paper discusses the use of modified Lotka-Volterra equations in order to stochastically simulate the behaviour of Listeria monocytogenes and Lactic Acid Bacteria (LAB) during the fermentation period (168 h) of a typical Sicilian salami. For this purpose, the differential equation system is set considering T, pH and aw as stochastic variables. Each of them is governed by dynamics that involve a deterministic linear decrease as a function of the time t and an "additive noise" term which instantaneously mimics the fluctuations of T, pH and aw. The choice of a suitable parameter accounting for the interaction of LAB on L. monocytogenes as well as the introduction of appropriate nois…
Spatio-temporal behaviour of the deep chlorophyll maximum in Mediterranean Sea: Development of a stochastic model for picophytoplankton dynamics
2013
In this paper, by using a stochastic reaction-diffusion-taxis model, we analyze the picophytoplankton dynamics in the basin of the Mediterranean Sea, characterized by poorly mixed waters. The model includes intraspecific competition of picophytoplankton for light and nutrients. The multiplicative noise sources present in the model account for random fluctuations of environmental variables. Phytoplankton distributions obtained from the model show a good agreement with experimental data sampled in two different sites of the Sicily Channel. The results could be extended to analyze data collected in different sites of the Mediterranean Sea and to devise predictive models for phytoplankton dynam…
The Determinants of Retail Productivity: A Critical Review of the Evidence
2009
This paper discusses the literature on the established determinants of productivity in the retail sector. It also draws attention to some neglected strands of research which provide useful insights into strategies that could allow productivity enhancements in this area of the economy. To date, very few attempts have been made to integrate different specialisms in order to explain what drives productivity in retail. Here this paper rectifies this omission by putting together studies from economics, geography, knowledge management and employment studies. It is the authors’ view that quantitative studies of retail productivity should focus on total factor productivity in retailing as the resul…
Modelling strategic alliances in the wide-body long range aircraft market
2007
Abstract The wide-body long-range aircrafts market is characterized by increasing rivalry between Airbus and Boeing. One of the factors that drive their strategic behaviour is technological. We propose a technology indicator to identify conditions under which the aircraft companies have incentives to join a coalition. For this, we provide measurement of the side-payments necessary to sign a strategic alliance aimed at reducing technological barriers in the market. The results suggest that the existence of side-payments guarantees the stability of a strategic alliance if the gap in the technological level between the firms is high, or competition is through prices. For monopoly, a strategic …
Shaping the firm's external search strategy
2014
This paper explores the determinants of external knowledge search strategies, specifically, exploitative and exploratory search. The literature emphasizes environmental context and technological resources, especially R&D, as important determinants of the search strategy. In this paper we focus on two types of the firm's formal structure: formalized and decentralized structures. The study uses survey data from the ceramic tile industry in Spain. The results show that a competitive environment and a decentralized organizational structure play a role in shaping the firm's external search strategy, but that R&D has no effect. We find that competition inhibits exploratory search, while a decentr…
Union structure and incentives for innovation
2002
Abstract In this paper, we consider the effect of union structure on the adoption of innovation in the context of Cournot duopoly. With a market size large enough, we show that the incentive to innovate is higher under a decentralized union structure (with each firm facing its own independent union) than under an industry-wide union. However, for a small market size (or, equivalently, for sufficiently drastic potential innovation), the new technology is more likely to be adopted in the presence of a centralized union. This result goes against the conventional view that unionization harms the incentive to innovate.
The relationship between professional tournament structure on the national level and success in men's professional tennis.
2003
This article discusses the relationship between a nation's men's professional tennis tournament structure and that nation's success in the international men's game. The 2002 men's professional tennis tournament calendar provided the distribution of events on the top thirty nations. Criteria for a nation's success in men's professional tennis were: nation's number of players with ATP points, nation's number of players in the top 200 ranking, and the combined ATP ranking of a nation's top 5 male players. Pearson correlations were performed between the number of tournaments and each criterion. Results showed a considerable variation in the number of events ranging between 67 (United States) an…