Queen's University Belfast

About: Queen's University Belfast is a education organization based out in Belfast, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 25457 authors who have published 55463 publications receiving 1751346 citations. The organization is also known as: Queen's College, Belfast & Queen's College.

KNN Model-Based Approach in Classification

Abstract: The k-Nearest-Neighbours (kNN) is a simple but effective method for classification The major drawbacks with respect to kNN are (1) its low efficiency – being a lazy learning method prohibits it in many applications such as dynamic web mining for a large repository, and (2) its dependency on the selection of a “good value” for k In this paper, we propose a novel kNN type method for classification that is aimed at overcoming these shortcomings Our method constructs a kNN model for the data, which replaces the data to serve as the basis of classification The value of k is automatically determined, is varied for different data, and is optimal in terms of classification accuracy The construction of the model reduces the dependency on k and makes classification faster Experiments were carried out on some public datasets collected from the UCI machine learning repository in order to test our method The experimental results show that the kNN based model compares well with C50 and kNN in terms of classification accuracy, but is more efficient than the standard kNN

DiveRsity: An R package for the estimation and exploration of population genetics parameters and their associated errors

Abstract: Summary We present a new R package, diveRsity, for the calculation of various diversity statistics, including common diversity partitioning statistics (θ, GST) and population differentiation statistics (DJost, GST ', χ2 test for population heterogeneity), among others. The package calculates these estimators along with their respective bootstrapped confidence intervals for loci, sample population pairwise and global levels. Various plotting tools are also provided for a visual evaluation of estimated values, allowing users to critically assess the validity and significance of statistical tests from a biological perspective. diveRsity has a set of unique features, which facilitate the use of an informed framework for assessing the validity of the use of traditional F-statistics for the inference of demography, with reference to specific marker types, particularly focusing on highly polymorphic microsatellite loci. However, the package can be readily used for other co-dominant marker types (e.g. allozymes, SNPs). Detailed examples of usage and descriptions of package capabilities are provided. The examples demonstrate useful strategies for the exploration of data and interpretation of results generated by diveRsity. Additional online resources for the package are also described, including a GUI web app version intended for those with more limited experience using R for statistical analysis.

The Theory of Scattering by a Rigid Rotator

Abstract: A theory of scattering by a rigid rotator in which the coupling between the different energy levels of the rotator is taken into account is formulated and explicit expressions, which do not depend upon the magnetic quantum numbers, are obtained for various elastic and inelastic cross-sections. Several approximations are described, particular attention being paid to the scattering of heavy particles for which it is shown that at low temperatures the orientation-dependent part of the interaction may be more important than the spherically symmetric part. The scattering of low-energy electrons is also investigated and some representative equations are integrated numerically to illustrate the effect of the orientation dependence.

Phylogeographic insights into cryptic glacial refugia.

Abstract: The glacial episodes of the Quaternary (2.6 million years ago–present) were a major factor in shaping the present-day distributions of extant flora and fauna, with expansions and contractions of the ice sheets rendering large areas uninhabitable for most species. Fossil records suggest that many species survived glacial maxima by retreating to refugia, usually at lower latitudes. Recently, phylogeographic studies have given support to the existence of previously unknown, or cryptic, refugia. Here we summarise many of these insights into the glacial histories of species in cryptic refugia gained through phylogeographic approaches. Understanding such refugia might be important as the Earth heads into another period of climate change, in terms of predicting the effects on species distribution and survival.