نتایج جستجو برای: divergence time estimation

تعداد نتایج: 2136009  

2011
Xiuling Zhou Ping Guo C. L. Philip Chen

Regularization is a solution to solve the problem of unstable estimation of covariance matrix with a small sample set in Gaussian classifier. And multi-regularization parameters estimation is more difficult than single parameter estimation. In this paper, KLIM_L covariance matrix estimation is derived theoretically based on MDL (minimum description length) principle for the small sample problem...

Journal: :Molecular ecology 2012
Yong Wang Rasmus Nielsen

The inference of population divergence times and branching patterns is of fundamental importance in many population genetic analyses. Many methods have been developed for estimating population divergence times, and recently, there has been particular attention towards genome-wide single-nucleotide polymorphisms (SNP) data. However, most SNP data have been affected by an ascertainment bias cause...

2014
Heidi E.L. Lischer Laurent Excoffier Gerald Heckel

Phylogenetic reconstruction of the evolutionary history of closely related organisms may be difficult because of the presence of unsorted lineages and of a relatively high proportion of heterozygous sites that are usually not handled well by phylogenetic programs. Genomic data may provide enough fixed polymorphisms to resolve phylogenetic trees, but the diploid nature of sequence data remains a...

ژورنال: اندیشه آماری 2020
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The minimum density power divergence method provides a robust estimate in the face of a situation where the dataset includes a number of outlier data. In this study, we introduce and use a robust minimum density power divergence estimator to estimate the parameters of the linear regression model and then with some numerical examples of linear regression model, we show the robustness of this est...

Journal: :Annals of statistics 2016
Qiyang Han Jon A Wellner

In this paper, we study the approximation and estimation of s-concave densities via Rényi divergence. We first show that the approximation of a probability measure Q by an s-concave density exists and is unique via the procedure of minimizing a divergence functional proposed by [Ann. Statist.38 (2010) 2998-3027] if and only if Q admits full-dimensional support and a first moment. We also show c...

Journal: Addiction and Health 2015
Ali Shahabifar, Ataollah Movahedinia

Background: The aim of the present study is to compare time perception among drug addicts and controls. Methods: 30 drug addicts were selected, and 30 non-addict individuals were selected as the control group. The two groups performed three tests of time reproduction, time estimation, and time discrimination. Findings: There was a significant difference between the addicts group and the control...

Journal: :Molecular biology and evolution 2015
Hui-Jie Lee Nicolas Rodrigue Jeffrey L Thorne

Rates of molecular evolution can vary over time. Diverse statistical techniques for divergence time estimation have been developed to accommodate this variation. These typically require that all sequence (or codon) positions at a locus change independently of one another. They also generally assume that the rates of different types of nucleotide substitutions vary across a phylogeny in the same...

2008
Shotaro Akaho Kazuya Takabatake

The contrastive divergence(CD) method proposed by Hinton finds an approximate solution of the maximum likelihood of complex probability models. It is known empirically that the CD method gives a high-quality estimation in a small computation time. In this paper, we give an intuitive explanation about the reason why the CD method can approximate well by using the information geometry. We further...

2007
Jon Sporring

Time to contact can be approximated from the divergence of the ow eld. Direct diierentiation of a measured ow eld is not feasible in practice because of the ill-posedness of diierentiation. We propose a group theoretical framework for direct determination of higher order ow elds. The basis is the invariance of the power spectrum of the Fourier transform to translations. By change of coordinate-...

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