890 resultados para Fisher Hypothesis


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In this Part 2 attention is turned towards the legal arrangements in nation states for managing wetlands. These national arrangements have effect within the international arrangements already mentioned and any regional arrangements that are relevant. However, each national system is a reflection of its own historical, cultural, political and constitutional background. It is the purpose of this Part 2 to review and assess the national approaches to wetlands management. This involves an analysis of a range of instruments. These are: constitutional rules; strategic rules; regulatory rules; and management rules. Each of these sets of rules performs different functions, assumes different forms and is differentially capable of enforcement.

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Interpersonal factors are crucial to a deepened understanding of depression. Belongingness, also referred to as connectedness, has been established as a strong risk/protective factor for depressive symptoms. To elucidate this link it may be beneficial to investigate the relative importance of specific psychosocial contexts as belongingness foci. Here we investigate the construct of workplace belongingness. Employees at a disability services organisation (N = 125) completed measures of depressive symptoms, anxiety symptoms, workplace belongingness and organisational commitment. Psychometric analyses, including Horn's parallel analyses, indicate that workplace belongingness is a unitary, robust and measurable construct. Correlational data indicate a substantial relationship with depressive symptoms (r = −.54) and anxiety symptoms (r = −.39). The difference between these correlations was statistically significant, supporting the particular importance of belongingness cognitions to the etiology of depression. Multiple regression analyses support the hypothesis that workplace belongingness mediates the relationship between affective organisational commitment and depressive symptoms. It is likely that workplaces have the potential to foster environments that are intrinsically less depressogenic by facilitating workplace belongingness. From a clinical perspective, cognitions regarding the workplace psychosocial context appear to be highly salient to individual psychological health, and hence warrant substantial attention.

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Elevated plasma fibronectin levels occur in various clinical states including arterial disease. Increasing evidence suggests that atherothrombosis and venous thromboembolism (VTE) share common risk factors. To assess the hypothesis that high plasma fibronectin levels are associated with VTE, we compared plasma fibronectin levels in the Scripps Venous Thrombosis Registry for 113 VTE cases vs. age and sex matched controls. VTE cases had significantly higher mean fibronectin concentration compared to controls (127% vs. 103%, p<0.0001); the difference was greater for idiopathic VTE cases compared to secondary VTE cases (133% vs. 120%, respectively). Using a cut-off of >90% of the control values, the odds ratio (OR) for association of VTE for fibronectin plasma levels above the 90th percentile were 9.37 (95% CI 2.73-32.2; p<0.001) and this OR remained significant after adjustment for sex, age, body mass index (BMI), factor V Leiden and prothrombin nt20210A (OR 7.60, 95% CI 2.14-27.0; p=0.002). In particular, the OR was statistically significant for idiopathic VTE before and after these statistical adjustments. For the total male cohort, the OR was significant before and after statistical adjustments and was not significant for the total female cohort. In summary, our results suggest that elevated plasma fibronectin levels are associated with VTE especially in males, and extend the potential association between biomarkers and risk factors for arterial atherothrombosis and VTE. © 2008 Schattauer GmbH.

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Given global demand for new infrastructure, governments face substantial challenges in funding new infrastructure and simultaneously delivering Value for Money (VfM). The paper begins with an update on a key development in a new early/first-order procurement decision making model that deploys production cost/benefit theory and theories concerning transaction costs from the New Institutional Economics, in order to identify a procurement mode that is likely to deliver the best ratio of production costs and transaction costs to production benefits, and therefore deliver superior VfM relative to alternative procurement modes. In doing so, the new procurement model is also able to address the uncertainty concerning the relative merits of Public-Private Partnerships (PPP) and non-PPP procurement approaches. The main aim of the paper is to develop competition as a dependent variable/proxy for VfM and a hypothesis (overarching proposition), as well as developing a research method to test the new procurement model. Competition reflects both production costs and benefits (absolute level of competition) and transaction costs (level of realised competition) and is a key proxy for VfM. Using competition as a proxy for VfM, the overarching proposition is given as: When the actual procurement mode matches the predicted (theoretical) procurement mode (informed by the new procurement model), then actual competition is expected to match potential competition (based on actual capacity). To collect data to test this proposition, the research method that is developed in this paper combines a survey and case study approach. More specifically, data collection instruments for the surveys to collect data on actual procurement, actual competition and potential competition are outlined. Finally, plans for analysing this survey data are briefly mentioned, along with noting the planned use of analytical pattern matching in deploying the new procurement model and in order to develop the predicted (theoretical) procurement mode.

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Research found that today’s organisations are increasingly aware of the potential barriers and perceived challenges associated with the successful delivery of change — including cultural and sub-cultural indifferences; financial constraints; restricted timelines; insufficient senior management support; fragmented key stakeholder commitment; and inadequate training. The delivery and application of Innovative Change (see glossary) within a construction industry organisation tends to require a certain level of ‘readiness’. This readiness is the combination of an organisation’s ability to part from undertakings that may be old, traditional, or inefficient; and then being able to readily adopt a procedure or initiative which is new, improved, or more efficient. Despite the construction industry’s awareness of the various threats and opportunities associated with the delivery of change, research found little attention is currently given to develop a ‘decision-making framework’ that comprises measurable elements (dynamics) that may assist in more accurately determining an organisation’s level of readiness or ability to deliver innovative change. To resolve this, an initial Background Literature Review in 2004 identified six such dynamics, those of Change, Innovation, Implementation, Culture, Leadership, and Training and Education, which were then hypothesised to be key components of a ‘Conceptual Decision-making Framework’ (CDF) for delivering innovative change within an organisation. To support this hypothesis, a second (more extensive) Literature Review was undertaken from late 2007 to mid 2009. A Delphi study was embarked on in June 2008, inviting fifteen building and construction industry members to form a panel and take part in a Delphi study. The selection criterion required panel members to have senior positions (manager and above) within a recognised field or occupation, and to have experience, understanding and / or knowledge in the process of delivering change within organisations. The final panel comprised nine representatives from private and public industry organisations and tertiary / research and development (R&D) universities. The Delphi study developed, distributed and collated two rounds of survey questionnaires over a four-month period, comprising open-ended and closed questions (referred to as factors). The first round of Delphi survey questionnaires were distributed to the panel in August 2008, asking them to rate the relevancy of the six hypothesised dynamics. In early September 2008, round-one responses were returned, analysed and documented. From this, an additional three dynamics were identified and confirmed by the panel as being highly relevant during the decision-making process when delivering innovative change within an organisation. The additional dynamics (‘Knowledge-sharing and Management’; ‘Business Process Requirements’; and ‘Life-cycle Costs’) were then added to the first six dynamics and used to populate the second (final) Delphi survey questionnaire. This was distributed to the same nine panel members in October 2008, this time asking them to rate the relevancy of all nine dynamics. In November 2008, round-two responses were returned, analysed, summarised and documented. Final results confirmed stability in responses and met Delphi study guidelines. The final contribution is twofold. Firstly, findings confirm all nine dynamics as key components of the proposed CDF for delivering innovative change within an organisation. Secondly, the future development and testing of an ‘Innovative Change Delivery Process’ (ICDP) is proposed, one that is underpinned by an ‘Innovative Change Decision-making Framework’ (ICDF), an ‘Innovative Change Delivery Analysis’ (ICDA) program, and an ‘Innovative Change Delivery Guide’ (ICDG).

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Many of the classification algorithms developed in the machine learning literature, including the support vector machine and boosting, can be viewed as minimum contrast methods that minimize a convex surrogate of the 0–1 loss function. The convexity makes these algorithms computationally efficient. The use of a surrogate, however, has statistical consequences that must be balanced against the computational virtues of convexity. To study these issues, we provide a general quantitative relationship between the risk as assessed using the 0–1 loss and the risk as assessed using any nonnegative surrogate loss function. We show that this relationship gives nontrivial upper bounds on excess risk under the weakest possible condition on the loss function—that it satisfies a pointwise form of Fisher consistency for classification. The relationship is based on a simple variational transformation of the loss function that is easy to compute in many applications. We also present a refined version of this result in the case of low noise, and show that in this case, strictly convex loss functions lead to faster rates of convergence of the risk than would be implied by standard uniform convergence arguments. Finally, we present applications of our results to the estimation of convergence rates in function classes that are scaled convex hulls of a finite-dimensional base class, with a variety of commonly used loss functions.

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Traders in the financial world are assessed by the amount of money they make and, increasingly, by the amount of money they make per unit of risk taken, a measure known as the Sharpe Ratio. Little is known about the average Sharpe Ratio among traders, but the Efficient Market Hypothesis suggests that traders, like asset managers, should not outperform the broad market. Here we report the findings of a study conducted in the City of London which shows that a population of experienced traders attain Sharpe Ratios significantly higher than the broad market. To explain this anomaly we examine a surrogate marker of prenatal androgen exposure, the second-to-fourth finger length ratio (2D:4D), which has previously been identified as predicting a trader's long term profitability. We find that it predicts the amount of risk taken by traders but not their Sharpe Ratios. We do, however, find that the traders' Sharpe Ratios increase markedly with the number of years they have traded, a result suggesting that learning plays a role in increasing the returns of traders. Our findings present anomalous data for the Efficient Markets Hypothesis.

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In the context of learning paradigms of identification in the limit, we address the question: why is uncertainty sometimes desirable? We use mind change bounds on the output hypotheses as a measure of uncertainty and interpret ‘desirable’ as reduction in data memorization, also defined in terms of mind change bounds. The resulting model is closely related to iterative learning with bounded mind change complexity, but the dual use of mind change bounds — for hypotheses and for data — is a key distinctive feature of our approach. We show that situations exist where the more mind changes the learner is willing to accept, the less the amount of data it needs to remember in order to converge to the correct hypothesis. We also investigate relationships between our model and learning from good examples, set-driven, monotonic and strong-monotonic learners, as well as class-comprising versus class-preserving learnability.

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The gonadotropin hypothesis proposes that elevated serum gonadotropin levels may increase the risk of epithelial ovarian cancer (EOC). We have studied the effect of treating EOC cell lines (OV207 and OVCAR-3) with FSH or LH. Both gonadotropins activated the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and increased cell migration that was inhibited by the MAPK 1 inhibitor PD98059. Both extra- and intracellular calcium ion signalling were implicated in gonadotropin-induced ERK1/2 activation as treatment with either the calcium chelator EGTA or an inhibitor of intracellular calcium release, dantrolene, inhibited gonadotropin-induced ERK1/2 activation. Verapamil was also inhibitory, indicating that gonadotropins activate calcium influx via L-type voltage-dependent calcium channels. The cAMP/protein kinase A (PKA) pathway was not involved in the mediation of gonadotropin action in these cells as gonadotropins did not increase intracellular cAMP formation and inhibition of PKA did not affect gonadotropin-induced phosphorylation of ERK1/2. Activation of ERK1/2 was inhibited by the protein kinase C (PKC) inhibitor GF 109203X as well as by the PKCδ inhibitor rottlerin, and downregulation of PKCδ was inhibited by small interfering RNA (siRNA), highlighting the importance of PKCδ in the gonadotropin signalling cascade. Furthermore, in addition to inhibition by PD98059, gonadotropin-induced ovarian cancer cell migration was also inhibited by verapamil, GF 109203X and rottlerin. Similarly, gonadotropin-induced proliferation was inhibited by PD98059, verapamil, GF 109203X and PKCδ siRNA. Taken together, these results demonstrate that gonadotropins induce both ovarian cancer cell migration and proliferation by activation of ERK1/2 signalling in a calcium- and PKCδ-dependent manner.

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The relationship between neuronal acuity and behavioral performance was assessed in the barn owl (Tyto alba), a nocturnal raptor renowned for its ability to localize sounds and for the topographic representation of auditory space found in the midbrain. We measured discrimination of sound-source separation using a newly developed procedure involving the habituation and recovery of the pupillary dilation response. The smallest discriminable change of source location was found to be about two times finer in azimuth than in elevation. Recordings from neurons in its midbrain space map revealed that their spatial tuning, like the spatial discrimination behavior, was also better in azimuth than in elevation by a factor of about two. Because the PDR behavioral assay is mediated by the same circuitry whether discrimination is assessed in azimuth or in elevation, this difference in vertical and horizontal acuity is likely to reflect a true difference in sensory resolution, without additional confounding effects of differences in motor performance in the two dimensions. Our results, therefore, are consistent with the hypothesis that the acuity of the midbrain space map determines auditory spatial discrimination.

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Axon guidance by molecular gradients plays a crucial role in wiring up the nervous system. However, the mechanisms axons use to detect gradients are largely unknown. We first develop a Bayesian “ideal observer” analysis of gradient detection by axons, based on the hypothesis that a principal constraint on gradient detection is intrinsic receptor binding noise. Second, from this model, we derive an equation predicting how the degree of response of an axon to a gradient should vary with gradient steepness and absolute concentration. Third, we confirm this prediction quantitatively by performing the first systematic experimental analysis of how axonal response varies with both these quantities. These experiments demonstrate a degree of sensitivity much higher than previously reported for any chemotacting system. Together, these results reveal both the quantitative constraints that must be satisfied for effective axonal guidance and the computational principles that may be used by the underlying signal transduction pathways, and allow predictions for the degree of response of axons to gradients in a wide variety of in vivo and in vitro settings.

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Presently, the manufacturing sector faces unprecedented levels of competition in both the domestic and international markets. This competition is mainly as a result of rapidly expanding international trade, gradual removal of protection, substantial reforms in labour markets and industrial relations, rapid technological changes and discerning customers. Intense global competition requires manufacturers to deliver products with higher quality in a shorter time. Simultaneously, owing to new technological innovations, the complexity of the products is increasing. In Australia, the impact of this intense competition and structural changes appear to be having negative effects on the manufacturing sector. This paper discusses the quality and reliability (Q & R) practices and associated drawbacks of Australian manufacturers and presents the findings of an investigation of the challenges Australian manufacturers are currently facing. The results reported in the paper are based on the data collected from a survey using the standard questionnaire. The study was driven by a conceptual model, which relates advanced quality practices to manufacturing performance and manufacturing difficulties.Evidence indicates that Q & R is the main competitive factor for Australian manufacturers. Design capability and on time delivery (OTD) came second. Results show that Australian manufacturers in general are facing some manufacturing difficulties. The relationship between advanced quality practices and company performance and manufacturing difficulties are explored. It is found that the companies who have more emphasis on advanced quality practices have fewer problems in manufacturing practices. Moreover, companies who have actively implemented the advanced quality practices have managed to improve the quality of the product continuously. The results validate the proposed hypothesis and lend credence to current thinking that improvement in Q & R is a vital tool for competitive advantage.