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Relative Costs (relative + cost)
Selected AbstractsSEX-RATIO CONFLICT BETWEEN QUEENS AND WORKERS IN EUSOCIAL HYMENOPTERA: MECHANISMS, COSTS, AND THE EVOLUTION OF SPLIT COLONY SEX RATIOSEVOLUTION, Issue 12 2005Ken R. Helms Abstract Because workers in the eusocial Hymenoptera are more closely related to sisters than to brothers, theory predicts that natural selection should act on them to bias (change) sex allocation to favor reproductive females over males. However, selection should also act on queens to prevent worker bias. We use a simulation approach to analyze the coevolution of this conflict in colonies with single, once-mated queens. We assume that queens bias the primary (egg) sex ratio and workers bias the secondary (adult) sex ratio, both at some cost to colony productivity. Workers can bias either by eliminating males or by directly increasing female caste determination. Although variation among colonies in kin structure is absent, simulations often result in bimodal (split) colony sex ratios. This occurs because of the evolution of two alternative queen or two alternative worker biasing strategies, one that biases strongly and another that does not bias at all. Alternative strategies evolve because the mechanisms of biasing result in accelerating benefits per unit cost with increasing bias, resulting in greater fitness for strategies that bias more and bias less than the population equilibrium. Strategies biasing more gain from increased biasing efficiency whereas strategies biasing less gain from decreased biasing cost. Our study predicts that whether queens or workers evolve alternative strategies depends upon the mechanisms that workers use to bias the sex ratio, the relative cost of queen and worker biasing, and the rates at which queen and worker strategies evolve. Our study also predicts that population and colony level sex allocation, as well as colony productivity, will differ diagnostically according to whether queens or workers evolve alternative biasing strategies and according to what mechanism workers use to bias sex allocation. [source] Modelling small-business credit scoring by using logistic regression, neural networks and decision treesINTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 3 2005Mirta Bensic Previous research on credit scoring that used statistical and intelligent methods was mostly focused on commercial and consumer lending. The main purpose of this paper is to extract important features for credit scoring in small-business lending on a dataset with specific transitional economic conditions using a relatively small dataset. To do this, we compare the accuracy of the best models extracted by different methodologies, such as logistic regression, neural networks (NNs), and CART decision trees. Four different NN algorithms are tested, including backpropagation, radial basis function network, probabilistic and learning vector quantization, by using the forward nonlinear variable selection strategy. Although the test of differences in proportion and McNemar's test do not show a statistically significant difference in the models tested, the probabilistic NN model produces the highest hit rate and the lowest type I error. According to the measures of association, the best NN model also shows the highest degree of association with the data, and it yields the lowest total relative cost of misclassification for all scenarios examined. The best model extracts a set of important features for small-business credit scoring for the observed sample, emphasizing credit programme characteristics, as well as entrepreneur's personal and business characteristics as the most important ones. Copyright © 2005 John Wiley & Sons, Ltd. [source] New immunochemical fecal occult blood test with two-consecutive stool sample testing is a cost-effective approach for colon cancer screening: Results of a prospective multicenter study in Chinese patientsINTERNATIONAL JOURNAL OF CANCER, Issue 12 2006Shirong Li Abstract The purpose of the study is to evaluate a new immunochemical fecal occult blood test method (Hemosure IFOBT), and compare it to the Guaiac-based chemical method (CFOBT) for colorectal cancer detection. A hypothetical sequential method (SFOBT), in which IFOBT was used only as a confirmatory test for CFOBT, was also evaluated. A total of 324 patients were recruited from 5 major hospitals in Beijing, China. For each patient, 3 consecutive stool samples were collected for simultaneous CFOBT and IFOBT tests, followed by colonoscopic examination. We compared the sensitivity and specificity of the 3 methods (CFOBT, IFOBT and SFOBT) in two settings, with the first 2 consecutive samples versus all 3 samples. Although the sensitivity for the detection of cancer and large (>20 mm) or multiple adenoma was similar for all 3 methods in the three-sample setting, in the two-sample setting IFOBT had higher sensitivity than SFOBT for detecting cancer (87.8% vs. 75.5%, respectively, p < 0.05) and large (>20 mm) or multiple adenomas (65.4% vs. 42.3%, respectively, p < 0.05). The IFOBT also had a higher specificity than the CFOBT (89.2% vs. 75.5%, respectively, p < 0.01) in "normal" individuals defined by colonoscopy in the three-sample setting. Comparing two-sample setting to the three-sample setting, both CFOBT and SFOBT showed significant loss of sensitivity for the detection of cancer as well as adenoma, whereas the sensitivity for IFOBT did not change significantly. Overall, IFOBT with two-sample testing showed compatible sensitivity and specificity to the three-sample testing, and had a lower relative cost per cancer detected than the three-sample testing. In conclusion, the new Hemosure IFOBT with two consecutive stool samples appears to be the most cost-effective approach for colon cancer screening. © 2006 Wiley-Liss, Inc. [source] Efficient organization of information processingMANAGERIAL AND DECISION ECONOMICS, Issue 1 2007Jacek Cukrowski The paper examines the application of the concept of economic efficiency to organizational issues of collective information processing in decision making. Information processing is modeled in the framework of the dynamic parallel processing model of associative computation with an endogenous setup cost of the processors. The model is extended to include the specific features of collective information processing in the team of decision makers which may lead to an error in data analysis. In such a model, the conditions for efficient organization of information processing are defined and the architecture of the efficient structures is considered. We show that specific features of collective decision making procedures require a broader framework for judging organizational efficiency than has traditionally been adopted. In particular, and contrary to the results available in economic literature, we show that there is no unique architecture for efficient information processing structures, but a number of various efficient forms. The results indicate that technological progress resulting in faster data processing (ceteris paribus) will lead to more regular information processing structures. However, if the relative cost of the delay in data analysis increases significantly, less regular structures could be efficient. Copyright © 2007 John Wiley & Sons, Ltd. [source] Bargaining in the Shadow of War: When Is a Peaceful Resolution Most Likely?AMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 3 2009Donald Wittman This article derives the optimal bargaining strategies of the belligerents when each side has private but incomplete information about the expected outcome of a war, should it take place. I show that the aggressor's demand curve can be below the defender's offer curve, that wars are possible even when both sides are jointly pessimistic, and that the relative cost of a war can radically alter the types of disputes that end in war. A simple diagram provides the intuition for most of the major propositions. [source] Predation and its rate of return: the sugar industry, 1887,1914THE RAND JOURNAL OF ECONOMICS, Issue 1 2006David Genesove We show that the price wars following two major entry episodes were predatory. Our proof is twofold: by direct comparison of price to marginal cost, and by construction of a lower bound to predicted competitive price-cost margins that we show to exceed observed margins. Predation occurred only when its relative cost to the dominant firm, the American Sugar Refining Company (ASRC), was small. Its most clear effect was to lower the acquisition price of entrants and small incumbents. It may also have deterred future capacity additions and raised ASRC's share of industry profits. Predation operated by strengthening ASRC's reputation as a willing predator. [source] The Multipredator Hypothesis and the Evolutionary Persistence of Antipredator BehaviorETHOLOGY, Issue 3 2006Daniel T. Blumstein Invited Review Abstract Isolation from predators affects prey behavior, morphology, and life history, but there is tremendous variation in the time course of these responses. Previous hypotheses to explain this variation have limited predictive ability. I develop a ,multipredator' hypothesis to explain the evolutionary persistence of antipredator behavior after the loss of some, but not all, of a species' predators. The hypothesis assumes pleiotropy, whereby elements of antipredator behavior may function in non-predatory situations, and linkage, such that genes influencing the expression of antipredator behavior do not assort independently. The hypothesis is restricted to species with multiple predators (most species) and aims to predict the conditions under which antipredator behavior will persist following the loss of one or more of a species' predators. I acknowledge that the relative costs of non-functional antipredator behavior will influence the likelihood of linkage and therefore persistence. The hypothesis makes two main predictions. First, genes responsible for antipredator behavior will not be scattered throughout the genome but rather may be found close together on the same chromosome(s). Secondly, the presence of any predators may be sufficient to maintain antipredator behavior for missing predators. Advances in behavioral genetics will allow tests of the first prediction, while studies of geographic variation in antipredator behavior provide some support for the second. [source] The police officer's terrorist dilemma: trust resilience following fatal errorsEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 6 2008Mathew P. White Suicide attacks have raised the stakes for officers deciding whether or not to shoot a suspect (,Police Officer's Terrorist Dilemma'). Despite high-profile errors we know little about how trust in the police is affected by their response to the terrorist threat. Building on a conceptualisation of lay observers as intuitive signal detection theorists, a general population sample (N,=,1153) were presented with scenarios manipulated in terms of suspect status (Armed/Unarmed), officer decision (Shoot/Not Shoot) and outcome severity (e.g. suspect armed with Bomb/Knife; police shoot suspect/suspect plus child bystander). Supporting predictions, people showed higher trust in officers who made correct decisions, reflecting good discrimination ability and who decided to shoot, reflecting an ,appropriate' response bias given the relative costs and benefits. This latter effect was moderated by (a) outcome severity, suggesting it did not simply reflect a preference for a particular type of action, and (b) preferences for a tough stance towards terrorism indexed by Right-Wing Authoritarianism (RWA). Despite loss of civilian life, failure to prevent minor terror attacks resulted in no loss of trust amongst people low in RWA, whereas among people high in RWA trust was positive when police erroneously shot an unarmed suspect. Relations to alternative definitions of trust and procedural justice research are discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] On the Aggregate Impact of Exchange Rate Variability on EU TradeGERMAN ECONOMIC REVIEW, Issue 1 2001Khalid Sekkat The paper assesses the aggregate impact of exchange rate variability on EU trade. A small econometric model is constructed and estimated for five countries: France, Italy, Germany, the UK and Belgium. The results show that there exists a long-term relationship between trade variables and relative costs, demand, exchange rates and expected exchange rates. No such relation exists with respect to volatility. It is also found that while the most important determinants of trade variables are relative wages and demand, variability is also responsible for a decrease in the growth rate of these variables. [source] Invited reaction: Cultivating problem-solving skills through problem-based approaches to professional developmentHUMAN RESOURCE DEVELOPMENT QUARTERLY, Issue 3 2002Richard E. Mayer In her article in this issue, Margaret Lohman distinguishes among four problem-based approaches to professional development: case study, goal-based scenario, problem-based learning, and action learning. Based on a review of more than a hundred articles, Lohman compares the four approaches in terms of the degree to which the problems used in the training are ill- versus well-defined and are either routine or nonroutine, the degree to which the training provides low versus high guidance, the degree to which the learning outcomes support near versus far transfer, and the relative costs of the approaches in terms of development and implementation. Future work is needed to (1) more sharply distinguish among the kinds of problem-based approaches to professional development, (2) relate problem-based training methods to cognitive theories of learning and problem solving, and (3) build a solid empirical research base for evaluating the cognitive outcomes of participation in various kinds of problem-based training. In particular, research is needed to determine which features of problem-based training promote which kinds of learning outcomes for which kinds of learners. [source] Off-site monitoring systems for predicting bank underperformance: a comparison of neural networks, discriminant analysis, and professional human judgmentINTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 3 2001Philip Swicegood This study compares the ability of discriminant analysis, neural networks, and professional human judgment methodologies in predicting commercial bank underperformance. Experience from the banking crisis of the 1980s and early 1990s suggest that improved prediction models are needed for helping prevent bank failures and promoting economic stability. Our research seeks to address this issue by exploring new prediction model techniques and comparing them to existing approaches. When comparing the predictive ability of all three models, the neural network model shows slightly better predictive ability than that of the regulators. Both the neural network model and regulators significantly outperform the benchmark discriminant analysis model's accuracy. These findings suggest that neural networks show promise as an off-site surveillance methodology. Factoring in the relative costs of the different types of misclassifications from each model also indicates that neural network models are better predictors, particularly when weighting Type I errors more heavily. Further research with neural networks in this field should yield workable models that greatly enhance the ability of regulators and bankers to identify and address weaknesses in banks before they approach failure. Copyright © 2001 John Wiley & Sons, Ltd. [source] Outcomes and Costs of Residential Services for Adults with Intellectual Disabilities in Taiwan: A Comparative EvaluationJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 2 2008Yueh-Ching Chou Background, The disability policy in Taiwan has traditionally emphasized residential care in large institutions and, more recently, medium-sized group homes. This paper compares the relative costs, services provided and outcomes between the traditional institutions, medium-sized group homes and new small-scale community living units that were launched in 2004 in Taiwan. Materials and Methods, Cross-sectional analysis was used to investigate the three current residential service models. A total of 248 participants with intellectual disabilities were interviewed, including all residents from the existing 25 small residential units and purposively sampled respondents from the other two residential models. Results, Outcomes for the Taiwanese participants were consistent with the existing literature on deinstitutionalization from Western societies. Small homes provided better subjective and objective quality of life than both medium-sized community-based units and traditional institutions. Conclusion, Participants living in small residential homes experienced better outcomes at lower cost than persons living in medium-sized group homes or institutions. [source] Sex allocation in black-capped chickadees Poecile atricapillaJOURNAL OF AVIAN BIOLOGY, Issue 2 2003Scott M. Ramsay Optimal sex allocation for individuals can be predicted from a number of different hypotheses. Fisherian models of sex allocation predict equal investment in males and females up to the end of parental care and predict brood compositions based on the relative costs of producing males and females. The Trivers-Willard hypothesis predicts that individual females should alter the sex ratio of their broods based on their own condition if it has a differential impact on the lifetime reproductive success of their sons and daughters. The Charnov model of sex allocation predicts that females should alter sex allocation based on paternal attributes that may differentially benefit sons versus daughters. Because females are the heterogametic sex in birds, many recent studies have focussed on primary sex ratio biases. In black-capped chickadees Poecile atricapilla, males are larger than females suggesting they may be more costly to raise than females. Female condition affects competitive ability in contests for mates, and thus may be related to variance in fecundity. Females prefer high-ranking males as both social and extrapair partners. These observations suggest that females might vary the sex ratio of their broods based on the predictions of any of the above models. Here, we report on the results of PCR based sex determination of 1093 nestlings in 175 broods sampled from 1992 to 2001. Population-wide, we found a mean brood sex ratio of 0.525±0.016, with no significant deviation from a predicted binomial distribution. We found no effect of clutch size, female condition, hatch date, parental rank or paternity. Our results reject the idea that female black-capped chickadees systematically vary sex allocation in their broods. [source] Effects of simulated browsing on growth and leaf chemical properties in Colophospermum mopane saplingsAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Edward M. Kohi Abstract Browsing intensity influences a plant's response to herbivory. Plants face a trade-off between investment in the production of secondary compounds and investment in growth. To elucidate this trade-off, we simulated four browsing intensities (0%, 50%, 75% and 100%) on mopane saplings, Colophospermum mopane (J. Kirk ex Benth.) J.Léonard, in a greenhouse experiment. This showed that, with increasing defoliation intensity, plants change their investment strategy. At intermediate levels of defoliation (50%), mopane saplings increased the synthesis of condensed tannins, so that tannin concentrations followed a hump-shaped relation with defoliation intensity, with significantly higher tannin concentration at intermediate defoliation levels. When defoliated heavily (75% and 100%), tannin concentrations dropped, and plants were carbon stressed as indicated by a reduced growth rate of the stem diameter, and leaf production and mean individual leaf mass were reduced. This suggests that, at intermediate defoliation intensity, the strategy of the plants is towards induced chemical defences. With increasing defoliation, the relative costs of the secondary metabolite synthesis become too high, and therefore, the plants change their growing strategy. Hence, browsers should be able to benefit from earlier browsing by either adopting a low or a relatively high browsing pressure. Résumé La réponse d'une plante à sa consommation dépend de l'intensité de ce phénomène. Les plantes sont confrontées à un compromis entre un investissement dans la production de composants secondaires et un investissement dans leur croissance. Pour élucider ce compromis, nous avons simulé quatre intensités de consommation (0%, 50%, 75% et 100%) sur des jeunes mopanes, Colophospermum mopane (J. Kirk ex Benth.) J.Leonard, lors d'expériences sous serre. Ceci a montré que, lorsque la défoliation s'intensifie, les plantes changent leur stratégie d'investissement. À des niveaux de défoliation intermédiaires (50%), les jeunes plants de mopanes augmentaient la synthèse de tanins condensés, de sorte que les concentrations en tanins suivaient une courbe en cloche (hump-shaped) selon l'intensité de la défoliation; elles étaient significativement plus élevées aux niveaux de défoliation intermédiaires. Lorsque les plantes sont fortement défoliées (75% et 100%), leurs concentrations en tanins chutent, et elles sont en stress carbone comme le montre le taux de croissance réduit du diamètre du tronc; la production de feuilles et la masse moyenne de feuilles par individu sont aussi réduites. Cela suggère que, quand l'intensité de défoliation est intermédiaire, la stratégie des plants va vers une défense chimique induite. Lorsque la défoliation augmente, le coût relatif de la synthèse du métabolite secondaire devient trop élevé et le plant change de stratégie de croissance. Donc, les herbivores qui les consomment devraient pouvoir bénéficier d'une consommation antérieure en adoptant une pression de consommation faible ou relativement élevée. [source] Evolution of a complex coevolved trait: active pollination in a genus of fig waspsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2004J. M. Cook Abstract Only three insect lineages have evolved complex active pollination behaviour and only fig wasps (Agaonidae) have also reverted from active to passive pollination. Previously, it was assumed that there was a single origin of active pollination in fig wasps, followed by one independent loss in each of five genera. We show here that there have been three to six changes in pollination behaviour within just one genus (Pleistodontes). The results suggest multiple gains of active pollination in fig wasps, but are sensitive to assumptions about the relative costs of gaining and losing this complex behaviour. In addition, previous comparative studies at higher taxonomic levels have reported correlated evolution between active pollination in wasps and low anther/ovule ratios in figs. We report that changes in pollination behaviour between congeneric species correlate perfectly with changes in anther/ovule ratios in the host figs, showing no phylogenetic inertia in coadaptation at the species level. [source] Gastro-oesophageal reflux disease in AsiaJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 3 2000Khean-Lee Goh Abstract Gastro-oesophageal reflux disease (GORD) occurs more frequently in Europe and North America than in Asia but its prevalence is now increasing in many Asian countries. Many reasons have been given for the lower prevalence of GORD in Asia. Low dietary fat and genetically determined factors, such as body mass index and maximal acid output, may be important. Other dietary factors appear to be less relevant. Increased intake of carbonated drinks or aggravating medicines may influence the increasing rates of GORD in some Asian countries but no strong evidence links other factors, such as the age of the population, smoking or alcohol consumption, to GORD. The management of GORD in Asia is similar to that in Europe and North America but the lower incidence of severe oesophagitis in Asia may alter the approach slightly. Also, because Asians tend to develop stomach cancer at an earlier age, endoscopy is used routinely at an earlier stage of investigation. Gastro-oesophageal reflux disease is essentially a motility disorder, so short-term management of the disease can usually be achieved using prokinetic agents (or histamine (H2)-receptor antagonists). More severe and recurrent GORD may require proton pump inhibitors (PPI) or a combination of prokinetic agents and PPI. The choice of long-term treatment may be influenced by the relative costs of prokinetic agents and PPI. © 2000 Blackwell Science Asia Pty Ltd [source] Women's fertility and mortality in late mid life: A comparison of three contemporary populationsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2009Emily Grundy Evolutionary theory suggests a trade-off between reproduction and somatic maintenance implying a negative relationship between parity and longevity, at least in natural fertility populations. In populations in which fertility control is usual, there are also a number of mechanisms that may link reproductive careers and later mortality, but evidence of associations between women's fertility patterns and their later life health has been judged inconclusive due to varying controls for socio-economic characteristics and marital status. Here, we build on three recent studies that followed a common framework to investigate associations between women's parity and timing of first and last birth with mortality in late middle age in three contemporary developed counties, Norway, England and Wales, and the USA. Data were drawn from whole population registers (Norway); a large census-based record linkage study (England and Wales), and a nationally representative survey linked to death records (USA). Results show that teenage childbirth was associated with higher mortality risks in late middle age in all three countries. Risks of death were significantly raised among nulliparous women in Norway and England and Wales, and also raised (although not significantly so) for childless US women. However, although higher parity was associated with a slight mortality disadvantage in England and Wales and the USA, the reverse seemed the case in Norway. These finding suggest that in populations in which fertility control is usual, contextual factors influencing the relative costs and benefits of childbearing may influence associations between fertility histories and later mortality. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] A design tool for planning emulsified oil-injection systemsREMEDIATION, Issue 4 2008Aaron M. Weispfenning Emulsified oils have been used to stimulate anaerobic bioremediation at hundreds of sites contaminated with chlorinated solvents, perchlorate, heavy metals, and nitrate. A simple spreadsheet-based tool has been developed to assist in the design of injection-only systems for distributing emulsified oils in barriers and area treatments. This tool allows users to quickly compare the relative costs and performance of different injection alternatives and identify a design that is best suited to site-specific conditions. Contact efficiency is estimated using results of prior numerical model simulations and dimensionless scaling factors that relate the volume of oil and water injected to treatment-zone dimensions. Sensitivity analysis results indicate that maximum oil retention is one of the most important factors controlling system performance and cost. © 2008 Wiley Periodicals, Inc. [source] Experimental field study of the relative costs and benefits to wild tamarins (saguinus imperator and S. fuscicollis) of exploiting contestable food patches as single- and mixed-species troopsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2003Júlio César Bicca-Marques Abstract Several species of tamarins form stable mixed-species troops in which groups of each species feed, forage, rest, and travel together during much of the year. Although the precise set of factors that facilitate this ecological relationship remains unclear, predator detection and foraging benefits are presumed to play a critical role in maintaining troop stability. In this work we present data from an experimental field study designed to examine how factors such as social dominance and within-patch foraging decisions affect the costs and benefits to tamarins of visiting feeding sites as single- and mixed-species troops. Our data indicate that when they exploited contestable food patches (sets of eight feeding platforms, two of which contained a 100-g banana), each tamarin species experienced foraging costs when they arrived as part of a mixed-species troop. These costs were found to be less severe for emperor tamarins because they were socially dominant to saddle-back tamarins and could displace them at feeding sites. We conclude that the foraging benefits to tamarins residing in mixed-species troops are asymmetrical, and that at feeding sites in which the amount of food in a patch is insufficient to satiate all troop members, even minor differences in the timing of return to food patches and changes in troop cohesion have a measurable effect on the costs and benefits to participating tamarin species. Am. J. Primatol. 60:139,153, 2003. © 2003 Wiley-Liss, Inc. [source] Ranked Set Sampling: Cost and Optimal Set SizeBIOMETRICS, Issue 4 2002Ramzi W. Nahhas Summary. Mclntyre (1952, Australian Journal of Agricultural Research3, 385,390) introduced ranked set sampling (RSS) as a method for improving estimation of a population mean in settings where sampling and ranking of units from the population are inexpensive when compared with actual measurement of the units. Two of the major factors in the usefulness of RSS are the set size and the relative costs of the various operations of sampling, ranking, and measurement. In this article, we consider ranking error models and cost models that enable us to assess the effect of different cost structures on the optimal set size for RSS. For reasonable cost structures, we find that the optimal RSS set sizes are generally larger than had been anticipated previously. These results will provide a useful tool for determining whether RSS is likely to lead to an improvement over simple random sampling in a given setting and, if so, what RSS set size is best to use in this case. [source] Does Canada Need Mandatory HACCP?CANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 4 2006Evidence from the Ontario Food Processing Sector The likelihood of the voluntary adoption of hazard analysis and critical control point (HACCP) among food processing firms is evaluated by exploring the perceptions of food safety managers with respect to a range of possible motivating factors including the exogenous pressure to adopt HACCP, efficacy of existing food safety controls, perception that HACCP will improve the firm's food safety controls, relative costs and benefits of HACCP implementation, impact of HACCP on business performance, and the nature of barriers to implementing HACCP. While market-based factors exert substantial pressure on firms to adopt HACCP, many food safety managers perceive that their existing food safety controls are adequate to meet existing food safety demands. While good manufacturing practice (GMP) and traceability are considered the most efficacious food safety controls, HACCP is most often perceived to provide intangible and "incidental" benefits that are often not recognized by food safety managers a priori. An important barrier to the voluntary adoption of HACCP is the perceived questionable appropriateness of HACCP for enhancing food safety controls, while financial constraints can be an absolute barrier to implementation. The results suggest a number of potential strategies through which the implementation of HACCP might be facilitated and enhanced through cooperation and coordination between regulators and industry organizations. La probabilité que les entreprises de transformation des aliments adoptent volontairement le système HACCP (analyse des risques et maîtrise des points critiques) a étéévaluée en examinant les perceptions des gestionnaires de sécurité alimentaire envers certains facteurs de motivation possibles tels que la pression exogène, l'efficacité des moyens de contrôle existants, la perception voulant que le système HACCP améliore le contrôle de la sécurité alimentaire de l'entreprise, les coûts et les avantages relatifs de la mise en place du système, les répercussions du système sur la performance de l'entreprise et la nature des obstacles à la mise en place du système. Bien que des facteurs de marché exercent d'importantes pressions pour que les entreprises adoptent ce système, de nombreux gestionnaires de sécurité alimentaire estiment que leurs moyens de contrôle existants répondent adéquatement aux demandes actuelles de sécurité alimentaire. Bien que les bonnes pratiques de fabrication (BPF) et la traçabilité soient considérées comme les moyens de contrôle de la sécurité alimentaire les plus efficaces, le système HACCP est le plus souvent perçu comme procurant des avantages intangibles et ,accessoires, qui, souvent, ne sont pas reconnus a priori par les gestionnaires de sécurité alimentaire. La pertinence discutable perçue du système HACCP comme moyen d'améliorer le contrôle de la sécurité alimentaire constitue un important obstacle à l'adoption volontaire du système, bien que les contraintes financières peuvent être un obstacle absolu à sa mise en place. Les résultats suggèrent un certain nombre de stratégies potentielles grâce auxquelles la mise en place du système pourrait être facilitée et améliorée par la collaboration et la coordination entre les organismes de réglementation et les entreprises de l'industrie de la transformation des aliments. [source] Action minimization and sharp-interface limits for the stochastic Allen-Cahn equationCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 3 2007Robert V. Kohn We study the action minimization problem that is formally associated to phase transformation in the stochastically perturbed Allen-Cahn equation. The sharp-interface limit is related to (but different from) the sharp-interface limits of the related energy functional and deterministic gradient flows. In the sharp-interface limit of the action minimization problem, we find distinct "most likely switching pathways," depending on the relative costs of nucleation and propagation of interfaces. This competition is captured by the limit of the action functional, which we derive formally and propose as the natural candidate for the ,-limit. Guided by the reduced functional, we prove upper and lower bounds for the minimal action that agree on the level of scaling. © 2006 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||