Local multiresolution order in community detection

Community detection algorithms attempt to find the best clusters of nodes in an arbitrary complex network. Multi-scale ("multiresolution") community detection extends the problem to identify the best network scale(s) for these clusters. The latter task is generally accomplished by analyzing community stability simultaneously for all clusters in the network. In the current work, we extend this general approach to define local multiresolution methods, which enable the extraction of well-defined local communities even if the global community structure is vaguely defined in an average sense. Toward this end, we propose measures analogous to variation of information and normalized mutual information that are used to quantitatively identify the best resolution(s) at the community level based on correlations between clusters in independently-solved systems. We demonstrate our method on two constructed networks as well as a real network and draw inferences about local community strength. Our approach is independent of the applied community detection algorithm save for the inherent requirement that the method be able to identify communities across different network scales, with appropriate changes to account for how different resolutions are evaluated or defined in a particular community detection method. It should, in principle, easily adapt to alternative community comparison measures.Comment: 19 pages, 11 figure

Consensus clustering in complex networks

The community structure of complex networks reveals both their organization and hidden relationships among their constituents. Most community detection methods currently available are not deterministic, and their results typically depend on the specific random seeds, initial conditions and tie-break rules adopted for their execution. Consensus clustering is used in data analysis to generate stable results out of a set of partitions delivered by stochastic methods. Here we show that consensus clustering can be combined with any existing method in a self-consistent way, enhancing considerably both the stability and the accuracy of the resulting partitions. This framework is also particularly suitable to monitor the evolution of community structure in temporal networks. An application of consensus clustering to a large citation network of physics papers demonstrates its capability to keep track of the birth, death and diversification of topics.Comment: 11 pages, 12 figures. Published in Scientific Report

Treatment of basal cell cancer in the periorbital area using a pulsed copper vapour laser

An increase in life expectancy in developed countries is inevitably accompanied by an increase in the number of nonmelanoma skin diseases, which are primarily represented by basal cell cancer (BCC) occurring in elderly and old-age patients. The pathogenesis of such diseases is associated both with impaired proliferation and differentiation of the keratinocytes of the epidermal basal layer, as well as with the transformation of the vasculature in the papillary dermis in the vicinity of BCC. In recent years, such conditions have been increasingly treated using CO2 , neodymium, diode and pulsed-dye lasers. In many cases, these devices allow malignant BCC cells to be successfully eliminated. However, the use of near-infrared lasers in the periorbital area is limited due to a higher risk of damaging the organs of the visual system. Therefore, a search for new laser surgery methods that can be used for treating malignant skin tumours seems to be a prospective research direction.Methods. 3 male and 9 female patients diagnosed with primary BCC were treated using a copper vapour laser (Yakhroma-Med). The age of the patients varied from 34 to 77 years. Laser treatment was carried out in one session under the following irradiation parameters: the wavelength of 511 and 578 nm, the average power of up to 3 W and a series of 15 ns pulses. The pause between the pulses was 60 μs, with the exposure time ranging from 200 to 600 ms. The light spot diameter on the skin surface was 1 mm. The follow-up monitoring duration was 24 months.Results. In all the BCC patients, one session of copper vapour laser treatment allowed malignant cells in the disease area to be completely eliminated without relapses during 2 years after the therapy. The duration of skin healing in the irradiated area was 2 weeks in patients under the age of 40 years, compared to 3–4 weeks in elderly patients. After the treatment, short-term side effects, such as a slight edema, erythema and peeling, were observed

Local Search is Underused in Genetic Programming

Trujillo, L., Z-Flores, E., Juárez-Smith, P. S., Legrand, P., Silva, S., Castelli, M., ... Muñoz, L. (2018). Local Search is Underused in Genetic Programming. In R. Riolo, B. Worzel, B. Goldman, & B. Tozier (Eds.), Genetic Programming Theory and Practice XIV (pp. 119-137). [8] (Genetic and Evolutionary Computation). Springer. https://doi.org/10.1007/978-3-319-97088-2_8There are two important limitations of standard tree-based genetic programming (GP). First, GP tends to evolve unnecessarily large programs, what is referred to as bloat. Second, GP uses inefficient search operators that focus on modifying program syntax. The first problem has been studied extensively, with many works proposing bloat control methods. Regarding the second problem, one approach is to use alternative search operators, for instance geometric semantic operators, to improve convergence. In this work, our goal is to experimentally show that both problems can be effectively addressed by incorporating a local search optimizer as an additional search operator. Using real-world problems, we show that this rather simple strategy can improve the convergence and performance of tree-based GP, while also reducing program size. Given these results, a question arises: Why are local search strategies so uncommon in GP? A small survey of popular GP libraries suggests to us that local search is underused in GP systems. We conclude by outlining plausible answers for this question and highlighting future work.authorsversionpublishe

Comparison of measures of marker informativeness for ancestry and admixture mapping

<p>Abstract</p> <p>Background</p> <p>Admixture mapping is a powerful gene mapping approach for an admixed population formed from ancestral populations with different allele frequencies. The power of this method relies on the ability of ancestry informative markers (AIMs) to infer ancestry along the chromosomes of admixed individuals. In this study, more than one million SNPs from HapMap databases and simulated data have been interrogated in admixed populations using various measures of ancestry informativeness: Fisher Information Content (FIC), Shannon Information Content (SIC), F statistics (F_ST), Informativeness for Assignment Measure (I_n), and the Absolute Allele Frequency Differences (delta, δ). The objectives are to compare these measures of informativeness to select SNP markers for ancestry inference, and to determine the accuracy of AIM panels selected by each measure in estimating the contributions of the ancestors to the admixed population.</p> <p>Results</p> <p>F_STand I_nhad the highest Spearman correlation and the best agreement as measured by Kappa statistics based on deciles. Although the different measures of marker informativeness performed comparably well, analyses based on the top 1 to 10% ranked informative markers of simulated data showed that I_nwas better in estimating ancestry for an admixed population.</p> <p>Conclusions</p> <p>Although millions of SNPs have been identified, only a small subset needs to be genotyped in order to accurately predict ancestry with a minimal error rate in a cost-effective manner. In this article, we compared various methods for selecting ancestry informative SNPs using simulations as well as SNP genotype data from samples of admixed populations and showed that the I_nmeasure estimates ancestry proportion (in an admixed population) with lower bias and mean square error.</p

Fast Learning In Multilayered Neural Networks By Means Of Hybrid Evolutionary And Gradient Algorithms

: This paper describes two algorithms based on cooperative evolution of internal hidden network representations and a combination of global evolutionary and local search procedures. The obtained experimental results are better in comparison with prototype methods. It is demonstrated, that the applications of pure gradient or pure genetic algorithms to the network training problem is much worse than hybrid procedures, which reasonably combine the advantages of global as well as local search. 1. INTRODUCTION Artificial Neural Networks (ANN) allows to approach effectively a large class of applications including pattern recognition, visual perception, signal processing and control systems. The most progress in this field is related to invention of the error backpropagation algorithm by Rumelhart et al. [1]. Backpropagation is now a conventional procedure for ANN training. However, the backpropagation as well as its numerous modifications, often leads to typical problems for gradient descen..