1,720,963 research outputs found
Defect Solutions of the Non-reciprocal Cahn-Hilliard Model: Spirals and Targets
Full text linkWe study the defect solutions of the Non-reciprocal Cahn-Hilliard model (NRCH). We find two kinds of defects, spirals with unit magnitude topological charge, and topologically neutral targets. These defects generate radially outward travelling waves and thus break the parity and time-reversal symmetry. For a given strength of non-reciprocity, spirals and targets with unique asymptotic wavenumber and amplitude are selected. We use large-scale simulations to show that at low non-reciprocity , a quenched disordered state evolves into quasi-stationary spiral networks. With increasing , we observe networks composed primarily of targets. Beyond a critical threshold , a disorder-order transition from defect networks to travelling waves emerges. The transition is marked by a sharp rise in the global polar order.15 pages including supplemental materia
Enhanced Stability and Chaotic Condensates in Multispecies Nonreciprocal Mixtures
No full textRandom nonreciprocal interactions between a large number of conserved densities are shown to enhance the stability of the system toward pattern formation. The enhanced stability is an exact result when the number of species approaches infinity and is confirmed numerically by simulations of the multispecies nonreciprocal Cahn-Hilliard model. Furthermore, the diversity in dynamical patterns increases with an increasing number of components, and novel steady states such as pulsating or spatiotemporally chaotic condensates are observed. Our results may help to unravel the mechanisms by which living systems self-organize via metabolism. Published by the American Physical Society 2025Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Max-Planck-Gesellschaft http://dx.doi.org/10.13039/501100004189Max Planck School Matter to LifeMaxSyn-Bio Consortiu
Inertia Drives Concentration-Wave Turbulence in Swimmer Suspensions
No full textDepartment of Atomic Energy, Government of India http://dx.doi.org/10.13039/501100001502Department of Science and Technology, Ministry of Science and Technology, India http://dx.doi.org/10.13039/501100001409Isaac Newton Institute for Mathematical Sciences http://dx.doi.org/10.13039/100012112Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/50110000026
Defect turbulence in a dense suspension of polar, active swimmers
Full text linkWe study the effects of inertia in dense suspensions of polar swimmers. The hydrodynamic velocity field and the polar order parameter field describe the dynamics of the suspension. We show that a dimensionless parameter (ratio of the swimmer self-advection speed to the active stress invasion speed) controls the stability of an ordered swimmer suspension. For smaller than a threshold , perturbations grow at a rate proportional to their wave number . Beyond , we show that the growth rate is until a second threshold is reached. The suspension is stable for . We perform direct numerical simulations to investigate the steady state properties and observe defect turbulence for . An investigation of the spatial organisation of defects unravels a hidden transition: for small defects are uniformly distributed and cluster as . Beyond , clustering saturates and defects are arranged in nearly string-like structures.8 pages, 7 figures, 1 appendi
Reachability and Controllability of Delayed Switched Boolean Control Networks
No full textIn this paper we investigate the reachability and controllability of delayed switched Boolean control networks (DSBCNs). By resorting to the algebraic state space representation method built using semi-tensor product (STP) of matrices, we provide several necessary and sufficient conditions for these properties to hold which are based on input-state incidence matrix carrying entire network dynamics information. Also, to realize the reachability of DSBCNs in shortest time, an algorithm is presented which finds switching and control sequences forcing initial state trajectory to destination state. At last, an example is given to illustrate the main results
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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