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To find interesting structure in networks, community detection algorithms have to take into account not only the network topology, but also dynamics of interactions between nodes. We investigate this claim using the paradigm of…

Social and Information Networks · Computer Science 2012-03-19 Rumi Ghosh , Kristina Lerman

Social systems are in a constant state of flux with dynamics spanning from minute-by-minute changes to patterns present on the timescale of years. Accurate models of social dynamics are important for understanding spreading of influence or…

Physics and Society · Physics 2017-01-02 Vedran Sekara , Arkadiusz Stopczynski , Sune Lehmann

Spectroscopic observations at extreme and far ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes,…

Solar and Stellar Astrophysics · Physics 2021-03-17 Hui Tian , Louise Harra , Deborah Baker , David H. Brooks , Lidong Xia

Observing the excitation mechanisms of incompressible transverse waves is vital for determining how energy propagates through the lower solar atmosphere. We aim to show the connection between convectively driven photospheric flows and…

Solar and Stellar Astrophysics · Physics 2015-06-15 R. J. Morton , G. Verth , V. Fedun , S. Shelyag , R. Erdélyi

Aims: We study the differences between non-magnetic and magnetic regions in the flow and thermal structure of the upper solar photosphere. Methods: Radiative MHD simulations representing a quiet region and a plage region, respectively,…

Solar and Stellar Astrophysics · Physics 2015-06-03 R. Moll , R. H. Cameron , M. Schüssler

We review (i) observations and numerical simulations of vortical flows in the solar atmosphere and (ii) measurements of the horizontal magnetic field in quiet Sun regions. First, we discuss various manifestations of vortical flows and…

Solar and Stellar Astrophysics · Physics 2012-02-21 O. Steiner , R. Rezaei

From the formation of animal flocks to the emergence of coordinate motion in bacterial swarms, at all scales populations of motile organisms display coherent collective motion. This consistent behavior strongly contrasts with the difference…

Soft Condensed Matter · Physics 2013-11-11 Antoine Bricard , Jean-Baptiste Caussin , Nicolas Desreumaux , Olivier Dauchot , Denis Bartolo

A number of biological processes, such as embryo development, cancer metastasis or wound healing, rely on cells moving in concert. The mechanisms leading to the emergence of coordinated motion remain however largely unexplored. Although…

Cell Behavior · Quantitative Biology 2011-08-23 Alexandre J Kabla

Coherent vortical motion has been reported in a wide variety of populations including living organisms (bacteria, fishes, human crowds) and synthetic active matter (shaken grains, mixtures of biopolymers), yet a unified description of the…

Waves and oscillations have been observed in the Sun's atmosphere for over half a century. While such phenomena have readily been observed across the entire electromagnetic spectrum, spanning radio to gamma-ray sources, the underlying role…

Solar and Stellar Astrophysics · Physics 2022-12-21 David B. Jess , Shahin Jafarzadeh , Peter H. Keys , Marco Stangalini , Gary Verth , Samuel D. T. Grant

We report on the occurrence of small-scale vortices in simulations of the convective solar surface. Using an eigenanalysis of the velocity gradient tensor, we find the subset of high vorticity regions in which the plasma is swirling. The…

Solar and Stellar Astrophysics · Physics 2015-05-30 R. Moll , R. H. Cameron , M. Schüssler

We examine discrete vortex dynamics in two-dimensional flow through a network-theoretic approach. The interaction of the vortices is represented with a graph, which allows the use of network-theoretic approaches to identify key…

Fluid Dynamics · Physics 2017-05-24 Aditya G. Nair , Kunihiko Taira

High-resolution observations of a quiet Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analyzed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the…

Solar and Stellar Astrophysics · Physics 2015-05-28 S. Vargas Dominguez , J. Palacios , L. Balmaceda , I. Cabello , V. Domingo

Photospheric vortex flows are thought to play a key role in the evolution of magnetic fields. Recent studies show that these swirling motions are ubiquitous in the solar surface convection and occur in a wide range of temporal and spatial…

Solar and Stellar Astrophysics · Physics 2018-03-07 Iker S. Requerey , Basilio Ruiz Cobo , Milan Gošić , Luis R. Bellot Rubio

Detection of community structures in social networks has attracted lots of attention in the domain of sociology and behavioral sciences. Social networks also exhibit dynamic nature as these networks change continuously with the passage of…

Social and Information Networks · Computer Science 2014-09-18 Frédéric Gilbert , Paolo Simonetto , Faraz Zaidi , Fabien Jourdan , Romain Bourqui

The Sun's atmosphere hosts swirling plasma structures, known as solar vortices, which have long been thought to channel wave energy into higher layers. Until now, no direct observations have confirmed their role in the heating of the…

The goal of community detection algorithms is to identify densely-connected units within large networks. An implicit assumption is that all the constituent nodes belong equally to their associated community. However, some nodes are more…

Social and Information Networks · Computer Science 2016-06-07 Tanmoy Chakraborty , Sriram Srinivasan , Niloy Ganguly , Animesh Mukherjee , Sanjukta Bhowmick

Communities are not static; they evolve, split and merge, appear and disappear, i.e. they are product of dynamical processes that govern the evolution of the network. A good algorithm for community detection should not only quantify the…

Physics and Society · Physics 2011-11-24 Angel Stanoev , Daniel Smilkov , Ljupco Kocarev

Previous studies have discovered a population of small granules with diameters less than 800 km showing differing physical properties. High resolution simulations and observations of the solar granulation, in combination with automated…

Solar and Stellar Astrophysics · Physics 2017-02-15 Birgit Lemmerer , Arnold Hanslmeier , Herbert Muthsam , Isabell Piantschitsch

Community detection methods have so far been tested mostly on small empirical networks and on synthetic benchmarks. Much less is known about their performance on large real-world networks, which nonetheless are a significant target for…

Physics and Society · Physics 2015-03-17 Gergely Tibely , Lauri Kovanen , Marton Karsai , Kimmo Kaski , Janos Kertesz , Jari Saramaki