scholarly journals Comparison of the FK5 Proper-Motion System with a Kinematic Distribution Function

1991 ◽  
Vol 127 ◽  
pp. 335-338
Author(s):  
Kavan U. Ratnatunga ◽  
Wayne H. Warren
Keyword(s):  
Distribution Function ◽  
Maximum Likelihood ◽  
Proper Motion ◽  
Global Maximum ◽  
Motion System ◽  
Trigonometric Parallax ◽  
Likelihood Analysis ◽  
Available Information ◽  
Independent Confirmation ◽  
Kinematic Distribution

AbstractA model for the kinematic distribution function of our Galaxy can be used as an independent confirmation that a reference system is free of Earth motions and retains the true kinematics of the stars. Maximum likelihood can simultaneously estimate the parameters required to calibrate distances to the stars, represent the kinematic distribution function, and check on residual Earth rotations in the proper-motion system. The global maximum-likelihood analysis uses all available information: photometry, trigonometric parallax, proper motion, and line-of-sight velocity for a well-defined catalog of stars. Awaiting observations from HIPPARCOS, preliminary testing of the algorithm on available ground-based observations is discussed.

scholarly journals MAXIMUM LIKELIHOOD ANALYSIS OF POPULATION DIFFERENCES IN ALLELIC FREQUENCIES

Genetics ◽  
1972 ◽  
Vol 72 (4) ◽  
pp. 709-719
Author(s):  
Peter E Smouse ◽  
Ken-Ichi Kojima
Keyword(s):  
Maximum Likelihood ◽  
Statistical Techniques ◽  
Ratio Test ◽  
Maximum Likelihood Analysis ◽  
Population Differences ◽  
Allelic Frequencies ◽  
Lack Of Fit ◽  
Likelihood Analysis ◽  
Test Criteria ◽  
Geographic Differences

ABSTRACT Statistical techniques are presented for the analysis of geographic variation in allelic frequencies. Likelihood ratio test criteria are derived from a multinominal sampling distribution, and are used to answer three questions. (1) Are there geographic differences in allelic frequencies? (2) Are population differences in allelic frequencies associated with environmental differences? (3) Is there any residual "lack of fit" variation among populations, after accounting for that variation associated with environmental differences? The two- and three-allele cases are explicitly treated, and the extension to more alleles is indicated.

A contribution towards the systematics of Magneuptychia Forster, 1964: Caeruleuptychia francisca (Butler, 1870), n. comb. (Lepidoptera: Nymphalidae: Satyrinae)

2020 ◽  
pp. 1-11
Author(s):  
Shinichi Nakahara ◽  
Kaylin Kleckner ◽  
Gerardo Lamas ◽  
Blanca Huertas ◽  
Keith R. Willmott
Keyword(s):  
Maximum Likelihood ◽  
Molecular Data ◽  
Maximum Likelihood Analysis ◽  
Maximum Likelihood Tree ◽  
Likelihood Analysis ◽  
First Time

We here transfer an euptychiine taxon hitherto placed in the polyphyletic genus Magneuptychia Forster, 1964, to Caeruleuptychia Forster, 1964. Caeruleuptychia francisca (Butler, 1870), n. comb. is reclassified based on a morphology-based maximum likelihood analysis, which is consistent with ongoing analyses of molecular data. Two putative synapomorphic characters are identified for the “Caeruleuptychia umbrosa clade”, one of which appears to be an unusual characteristic of euptychiine butterflies and is tested by optimizing onto the maximum likelihood tree. We also discuss the systematic placement of three additional enigmatic Caeruleuptychia species. A lectotype is designated for Euptychia francisca, and the genitalia of this species are illustrated here for the first time.

scholarly journals The Gaia-ESO Survey: membership probabilities for stars in 32 open clusters from 3D kinematics

2020 ◽  
Vol 496 (4) ◽  
pp. 4701-4716 ◽  
Author(s):  
R J Jackson ◽  
R D Jeffries ◽  
N J Wright ◽  
S Randich ◽  
G Sacco ◽  
...  
Keyword(s):  
Maximum Likelihood ◽  
Proper Motion ◽  
Milky Way ◽  
Open Clusters ◽  
Evolutionary Models ◽  
Valuable Resource ◽  
3D Kinematics ◽  
Cluster Membership ◽  
Data Release ◽  
Average Probability

ABSTRACT The Gaia-ESO Survey (GES) observed many open clusters as part of its programme to spectroscopically characterize the various Milky Way populations. GES spectroscopy and Gaia astrometry from its second data release are used here to assign membership probabilities to targets towards 32 open clusters with ages from 1 to 3800 Myr, based on maximum likelihood modelling of the 3D kinematics of the cluster and field populations. From a parent catalogue of 14 398 individual targets, 5032 stars with uniformly determined 3D velocities, Teff, log g, and chemistry are assigned cluster membership with probability >0.9, and with an average probability of 0.991. The robustness of the membership probabilities is demonstrated using independent membership criteria (lithium and parallax) in two of the youngest clusters. The addition of radial velocities improves membership discrimination over proper motion selection alone, especially in more distant clusters. The kinematically selected nature of the membership lists, independent of photometry and chemistry, makes the catalogue a valuable resource for testing stellar evolutionary models and investigating the time evolution of various parameters.

scholarly journals Automatic Spike Sorting Using Tuning Information

2009 ◽  
Vol 21 (9) ◽  
pp. 2466-2501 ◽  
Author(s):  
Valérie Ventura
Keyword(s):  
Maximum Likelihood ◽  
Expectation Maximization ◽  
Poisson Processes ◽  
Spike Sorting ◽  
Maximum Likelihood Algorithm ◽  
Firing Rates ◽  
Novel Approach ◽  
Misclassification Rates ◽  
Available Information ◽  
Spike Waveforms

Current spike sorting methods focus on clustering neurons' characteristic spike waveforms. The resulting spike-sorted data are typically used to estimate how covariates of interest modulate the firing rates of neurons. However, when these covariates do modulate the firing rates, they provide information about spikes' identities, which thus far have been ignored for the purpose of spike sorting. This letter describes a novel approach to spike sorting, which incorporates both waveform information and tuning information obtained from the modulation of firing rates. Because it efficiently uses all the available information, this spike sorter yields lower spike misclassification rates than traditional automatic spike sorters. This theoretical result is verified empirically on several examples. The proposed method does not require additional assumptions; only its implementation is different. It essentially consists of performing spike sorting and tuning estimation simultaneously rather than sequentially, as is currently done. We used an expectation-maximization maximum likelihood algorithm to implement the new spike sorter. We present the general form of this algorithm and provide a detailed implementable version under the assumptions that neurons are independent and spike according to Poisson processes. Finally, we uncover a systematic flaw of spike sorting based on waveform information only.

A survey of proper-motion stars. VII - The halo metallicity distribution function

1988 ◽  
Vol 96 ◽  
pp. 1908 ◽  
Author(s):  
John B. Laird ◽  
Bruce W. Carney ◽  
Michael P. Rupen ◽  
David W. Latham
Keyword(s):  
Distribution Function ◽  
Proper Motion ◽  
Metallicity Distribution

Animal x testing environment interaction on postweaning liveweight gains of young bulls

1998 ◽  
Vol 49 (4) ◽  
pp. 607 ◽  
Author(s):  
S. J. Schoeman ◽  
G. G. Jordaan
Keyword(s):  
Maximum Likelihood ◽  
Genetic Correlation ◽  
Variance Components ◽  
Restricted Maximum Likelihood ◽  
Animal Breeding ◽  
Environment Interaction ◽  
Maximum Likelihood Analysis ◽  
Breeding Values ◽  
Testing Environment ◽  
Likelihood Analysis

Postweaning liveweight gain records of 1610 young bulls obtained both in feedlot and under pasture were used to estimate (co)variance components using a multivariate restricted maximum likelihood analysis. The pedigree file included 3477 animals. Heritability estimates for liveweights and gain in both environments correspond to most previously reported estimates. The genetic correlation of gain between the 2 environments was -0·12, suggesting a large genotype testing environment interaction and re-ranking of animal breeding values across environments. Results of this analysis suggest the need for environment-specific breeding values for postweaning gain.

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