56,853 research outputs found
Bayesian Nonparametric Construction of the Fleming-Viot Process with Fertility Selection
No full textThis paper provides the construction in a Bayesian setting of the Fleming-Viot measurevalued process with diploid fertility selection and highlights new connections between Bayesian nonparametrics and population genetics. Via a generalisation of the Blackwell-MacQueen Polya-urn scheme, a Markov particle process is defined such that the associated process of empirical measures converges to the Fleming-Viot diffusion. The stationary distribution, known from Ethier and Kurtz (1994), is then derived through an application of the Dirichlet process mixture model and shown to be the de Finetti measure of the particle process. The Fleming-Viot process with haploid selection is derived as a special case.Fleming-Viot process; Measure-valued process; Fertility selection; Gibbs sampler; Dirichlet process mixture model; Blackwell-MacQueen urn-scheme
A Fleming-Viot process and Bayesian nonparametrics
No full textThis paper provides a construction of a Fleming-Viot measure valued diffusion process, for which the transition function is known, by extending recent ideas of the Gibbs sampler based Markov processes. In particular, we concentrate on the Chapman-Kolmogorov consistency conditions which allows a simple derivation of such a Fleming-Viot process, once a key and apparently new combinatorial result for Polya-urn sequences has been establishe
On the Origins of the Fleming-Mundell Model
No full textForty years ago, Marcus Fleming and Robert Mundell developed independent models of macroeconomic policy in open economies. Why do we link the two, and why do we call the result the Mundell-Fleming, rather than Fleming-Mundell model? Copyright 2003, International Monetary Fund
Construction and Stationary Distribution of the Fleming-Viot Process with Viability Selection
No full textThis paper provides an explicit construction of the Fleming-Viot process with viability selection in a Bayesian nonparametric framework, and derives its stationary distribution. The measure-valued diffusion is obtained as the infinite population limit of the empirical measures of a semi-Markov process of exchangeable particles. In the limit the stationary distribution is shown to be the two-parameter Poisson-Dirichlet process, also known as the Pitman-Yor process.Fleming-Viot process; semi-Markov process; viability selection; stationary distribution; two-parameter Poisson-Dirichlet process.
Multiobjective gas turbine engine controller design using genetic algorithms
No full textThis paper describes the use of multiobjective genetic algorithms (MOGAs) in the design of a multivariable control system for a gas turbine engine. The mechanisms employed to facilitate multiobjective search with the genetic algorithm are described with the aid of an example. It is shown that the MOGA confers a number of advantages over conventional multiobjective optimization methods by evolving a family of Pareto-optimal solutions rather than a single solution estimate. This allows the engineer to examine the trade-offs between the different design objectives and configurations during the course of an optimization. In addition, the paper demonstrates how the genetic algorithm can be used to search in both controller structure and parameter space thereby offering a potentially more general approach to optimization in controller design than traditional numerical methods. While the example in the paper deals with control system design, the approach described can be expected to be applicable to more general problems in the fields of computer aided design (CAD) and computer aided engineering (CAE
Most recommended medical interventions reach P<0.005 for their primary outcomes in meta-analyses
No full textBackground: It has been proposed that the threshold of statistical significance should shift from P-value < 0.05 to P-value < 0.005, but there is concern that this move may dismiss effective, useful interventions. We aimed to assess how often medical interventions are recommended although their evidence in meta-analyses of randomized trials lies between P-value = 0.05 and P-value = 0.005.
Methods: We included Cochrane systematic reviews (SRs) published from 1 January 2013 to 30 June 2014 that had at least one meta-analysis with GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessment and at least one primary outcome having favourable results for efficacy at P-value < 0.05. Only comparisons of randomized trials between active versus no treatment/placebo were included. We then assessed the respective UpToDate recommendations for clinical practice from 22 May 2018 to 5 October 2018 and recorded how many treatments were recommended and what were the P-values in their meta-analysis evidence. The primary analysis was based on the first-listed outcomes.
Results: Of 608 screened SRs with GRADE assessment, 113 SRs were eligible, including 143 comparisons of which 128 comparisons had first-listed primary outcomes with UpToDate coverage. Altogether, 60% (58/97) of interventions with P-values < 0.005 for their evidence were recommended versus 32% (10/31) of those with P-value 0.005-0.05. Therefore, most (58/68, 85.2%) of the recommended interventions had P-values < 0.005 for the first-listed primary outcome. Of the 10 exceptions, 4 had other primary outcomes with P-values < 0.005 and another 4 had additional extensive evidence for similar indications that would allow extrapolation for practice recommendations.
Conclusions: Few interventions are recommended without their evidence from meta-analyses of randomized trials reaching P-value < 0.005.
Keywords: P-value; Cochrane; UpToDate; meta-analysis; recommendation; statistical threshold
A Flaming-Viot Process and Bayesian non Parametric
No full textThis paper provides a construction of a Fleming-Viot measure valued diffusion process, for which the transition function is known, by extending recent ideas of Gibbs sampler based Markov processes. In particular, we concentrate on the Chapman-Kolmogorov consistency conditions which allows a simple derivation of such a Fleming-Viot process, once a key, and apparently new combinatorial result for P´olya-urn sequences has been established.Chapman-Kolmogorov; Diffusion process; Dirichlet process; Polyaurn scheme; Population genetics.
Early Embryo Environment and Developmental Potential
No full textTom P. Fleming, Kevin D. Sinclair and Karen L. Kindhttp://nla.gov.au/anbd.bib-an4394992
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
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