8 research outputs found
k-core (bootstrap) percolation on complex networks: Critical phenomena and nonlocal effects
We develop the theory of the k-core (bootstrap) percolation on uncorrelated
random networks with arbitrary degree distributions. We show that the k-core
percolation is an unusual, hybrid phase transition with a jump emergence of the
k-core as at a first order phase transition but also with a critical
singularity as at a continuous transition. We describe the properties of the
k-core, explain the meaning of the order parameter for the k-core percolation,
and reveal the origin of the specific critical phenomena. We demonstrate that a
so-called ``corona'' of the k-core plays a crucial role (corona is a subset of
vertices in the k-core which have exactly k neighbors in the k-core). It turns
out that the k-core percolation threshold is at the same time the percolation
threshold of finite corona clusters. The mean separation of vertices in corona
clusters plays the role of the correlation length and diverges at the critical
point. We show that a random removal of even one vertex from the k-core may
result in the collapse of a vast region of the k-core around the removed
vertex. The mean size of this region diverges at the critical point. We find an
exact mapping of the k-core percolation to a model of cooperative relaxation.
This model undergoes critical relaxation with a divergent rate at some critical
moment.Comment: 11 pages, 8 figure
Heterogeneous slow dynamics in a two dimensional doped classical antiferromagnet
We introduce a lattice model for a classical doped two dimensional
antiferromagnet which has no quenched disorder, yet displays slow dynamics
similar to those observed in supercooled liquids. We calculate two-time spatial
and spin correlations via Monte Carlo simulations and find that for
sufficiently low temperatures, there is anomalous diffusion and
stretched-exponential relaxation of spin correlations. The relaxation times
associated with spin correlations and diffusion both diverge at low
temperatures in a sub-Arrhenius fashion if the fit is done over a large
temperature-window or an Arrhenius fashion if only low temperatures are
considered. We find evidence of spatially heterogeneous dynamics, in which
vacancies created by changes in occupation facilitate spin flips on
neighbouring sites. We find violations of the Stokes-Einstein relation and
Debye-Stokes-Einstein relation and show that the probability distributions of
local spatial correlations indicate fast and slow populations of sites, and
local spin correlations indicate a wide distribution of relaxation times,
similar to observ ations in other glassy systems with and without quenched
disorder.Comment: 12 pages, 17 figures, corrected erroneous figure, and improved
quality of manuscript, updated reference
Morphology transition at depinning in a solvable model of interface growth in a random medium
L'éruption du volcan Hunga Tonga -Hunga Ha'apai le 15 janvier 2022 : un ébranlement du systÚme Terre à l'échelle planétaire
L'Ă©ruption explosive du volcan Hunga Tonga - Hunga Haâapai (HTHH), le 15 janvier 2022, a produit la plus puissante explosion enregistrĂ©e depuis les explosions du Krakatau et du Tambora dans les annĂ©es 1800, libĂ©rant une Ă©nergie Ă©quivalente Ă 110 mĂ©gatonnes de TNT. Les ondes gĂ©nĂ©rĂ©es sesont propagĂ©es dans le sol, et dans lâatmosphĂšre jusquâĂ lâionosphĂšre. L'onde atmosphĂ©rique la plus Ă©nergĂ©tique observĂ©e sur les baromĂštres correspond au mode de Lamb. De pĂ©riode supĂ©rieure Ă 2000 s, son amplitude est comparable Ă celle observĂ©e lors de lâĂ©ruption du Krakatau en 1883. Lâempreinte des perturbations atmosphĂ©riques a Ă©tĂ© caractĂ©risĂ©e Ă lâĂ©chelle planĂ©taire par des rĂ©seaux de mesures au sol, Ă bord de satellites ou de plateformes aĂ©roportĂ©es. Lâanalyse combinĂ©e de ces observations a permis dâĂ©valuer les consĂ©quences Ă court terme de l'Ă©ruption du HTHH. Les mĂ©thodes d'investigation gĂ©ophysiques prĂ©sentĂ©es dans cette note montrent lâapport dâanalyses interdisciplinaires pour caractĂ©riser la rĂ©ponse impulsionnelle des enveloppes fluides planĂ©taires (atmosphĂšre, ocĂ©ans et mers) Ă une Ă©ruption dâune intensitĂ© exceptionnelle
L'éruption du volcan Hunga Tonga -Hunga Ha'apai le 15 janvier 2022 : un ébranlement du systÚme Terre à l'échelle planétaire
L'Ă©ruption explosive du volcan Hunga Tonga - Hunga Haâapai (HTHH), le 15 janvier 2022, a produit la plus puissante explosion enregistrĂ©e depuis les explosions du Krakatau et du Tambora dans les annĂ©es 1800, libĂ©rant une Ă©nergie Ă©quivalente Ă 110 mĂ©gatonnes de TNT. Les ondes gĂ©nĂ©rĂ©es sesont propagĂ©es dans le sol, et dans lâatmosphĂšre jusquâĂ lâionosphĂšre. L'onde atmosphĂ©rique la plus Ă©nergĂ©tique observĂ©e sur les baromĂštres correspond au mode de Lamb. De pĂ©riode supĂ©rieure Ă 2000 s, son amplitude est comparable Ă celle observĂ©e lors de lâĂ©ruption du Krakatau en 1883. Lâempreinte des perturbations atmosphĂ©riques a Ă©tĂ© caractĂ©risĂ©e Ă lâĂ©chelle planĂ©taire par des rĂ©seaux de mesures au sol, Ă bord de satellites ou de plateformes aĂ©roportĂ©es. Lâanalyse combinĂ©e de ces observations a permis dâĂ©valuer les consĂ©quences Ă court terme de l'Ă©ruption du HTHH. Les mĂ©thodes d'investigation gĂ©ophysiques prĂ©sentĂ©es dans cette note montrent lâapport dâanalyses interdisciplinaires pour caractĂ©riser la rĂ©ponse impulsionnelle des enveloppes fluides planĂ©taires (atmosphĂšre, ocĂ©ans et mers) Ă une Ă©ruption dâune intensitĂ© exceptionnelle