Three-fold way to extinction in populations of cyclically competing species

Species extinction occurs regularly and unavoidably in ecological systems. The time scales for extinction can broadly vary and inform on the ecosystem's stability. We study the spatio-temporal extinction dynamics of a paradigmatic population model where three species exhibit cyclic competition. The cyclic dynamics reflects the non-equilibrium nature of the species interactions. While previous work focusses on the coarsening process as a mechanism that drives the system to extinction, we found that unexpectedly the dynamics to extinction is much richer. We observed three different types of dynamics. In addition to coarsening, in the evolutionary relevant limit of large times, oscillating traveling waves and heteroclinic orbits play a dominant role. The weight of the different processes depends on the degree of mixing and the system size. By analytical arguments and extensive numerical simulations we provide the full characteristics of scenarios leading to extinction in one of the most surprising models of ecology

Near-optimal asymmetric binary matrix partitions

We study the asymmetric binary matrix partition problem that was recently introduced by Alon et al. (WINE 2013) to model the impact of asymmetric information on the revenue of the seller in take-it-or-leave-it sales. Instances of the problem consist of an $n \times m$ binary matrix $A$ and a probability distribution over its columns. A partition scheme $B=(B_1,...,B_n)$ consists of a partition $B_i$ for each row $i$ of $A$. The partition $B_i$ acts as a smoothing operator on row $i$ that distributes the expected value of each partition subset proportionally to all its entries. Given a scheme $B$ that induces a smooth matrix $A^B$, the partition value is the expected maximum column entry of $A^B$. The objective is to find a partition scheme such that the resulting partition value is maximized. We present a $9/10$-approximation algorithm for the case where the probability distribution is uniform and a $(1-1/e)$-approximation algorithm for non-uniform distributions, significantly improving results of Alon et al. Although our first algorithm is combinatorial (and very simple), the analysis is based on linear programming and duality arguments. In our second result we exploit a nice relation of the problem to submodular welfare maximization.Comment: 17 page

Rankings as a comprehensive model to assess innovation and investment development of mesolevel economic systems (case of Tomsk region)

Актуальность определяется растущим интересом зарубежных и отечественных исследователей и практиков к рейтингам как комплексному методу оценки инновационно‐инвестиционого развития регионов. При этом нет единства мнений по методикам формирования рейтингов, отбора показателей и методов расчета. Цель работы: исследование и анализ рейтингов как модели комплексной оценки инновационного и инвестиционного развития экономических систем мезоуровня. Методы исследования: методы сравнительного, логического анализа, анализ и синтез, системный подход. Результаты. Представлен сравни‐ тельный анализ российских инновационно‐инвестиционных рейтингов; рассмотрены методики их составления и используемые системы показателей. Сформулированы ограничения рейтинга как модели комплексной оценки в целом, дана характеристика каждого отдельного рейтинга. В качестве примеров приведены позиции регионов Сибирского федерального округа в пяти российских рейтингах.The relevance of the topic is determined by the growing interest of foreign and domestic researchers and practitioners in ratings as a comprehensive method for assessing the innovative and investment development of the regions. At the same time there is no unity of opinion on the methods of rating formation, selection of indicators and calculation methods. The aim of the study is to research and analyze ratings as a model for integrated assessment of innovation and investment development of meso‐level economic systems. Methods of research: methods of comparative, logical analysis, analysis and synthesis, systematic approach. Results. The paper introduces the comparative analysis of Russian innovation and investment ratings, considers the methods of their compilation and the system of indicators. The rating constraints are formulated as a model of integrated assessment in general, and the characteristics of each individual rating are given. The authors give the positions of the regions of the Siberian Federal District in five Russian rankings as an example

Images of psychiatry and psychiatrists

Peer reviewedPublisher PD

Sorting of chromosomes by magnetic separation

Chromosomes were isolated from Chinese hamster x human hybrid cell lines containing four and nine human chromosomes. Human genomic DNA was biotinylated by nick translation and used to label the human chromosomes by in situ hybridization in suspension. Streptavidin was covalently coupled to the surface of magnetic beads and these were incubated with the hybridized chromosomes. The human chromosomes were bound to the magnetic beads through the strong biotin-streptavidin complex and then rapidly separated from nonlabeled Chinese hamster chromosomes by a simple permanent magnet. The hybridization was visualized by additional binding of avidin-FITC (fluorescein) to the unoccupied biotinylated human DNA bound to the human chromosomes. After magnetic separation, up to 98% of the individual chromosomes attached to magnetic beads were classified as human chromosomes by fluorescence microscopy

Laser-UV-microirradiation of interphase nuclei and posttreatment with caffeine: a new approach to establish the arrangement of interphase chromosomes

Laser UV microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: I) intact metaphase figures, II) chromosome damage confined to a small area of the metaphase spread, III) mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus

The origin of human chromosome 2 analyzed by comparative chromosome mapping with a DNA microlibrary

Fluorescencein situ hybridization (FISH) of microlibraries established from distinct chromosome subregions can test the evolutionary conservation of chromosome bands as well as chromosomal rearrangements that occurred during primate evolution and will help to clarify phylogenetic relationships. We used a DNA library established by microdissection and microcloning from the entire long arm of human chromosome 2 for fluorescencein situ hybridization and comparative mapping of the chromosomes of human, great apes (Pan troglodytes, Pan paniscus, Gorilla gorilla, Pongo pygmaeus) and Old World monkeys (Macaca fuscata andCercopithecus aethiops). Inversions were found in the pericentric region of the primate chromosome 2p homologs in great apes, and the hybridization pattern demonstrates the known phylogenetically derived telomere fusion in the line that leads to human chromosome 2. The hybridization of the 2q microlibrary to chromosomes of Old World monkeys gave a different pattern from that in the gorilla and the orang-utan, but a pattern similar to that of chimpanzees. This suggests convergence of chromosomal rearrangements in different phylogenetic lines