260 research outputs found
Seed selection for information cascade in multilayer networks
Information spreading is an interesting field in the domain of online social
media. In this work, we are investigating how well different seed selection
strategies affect the spreading processes simulated using independent cascade
model on eighteen multilayer social networks. Fifteen networks are built based
on the user interaction data extracted from Facebook public pages and tree of
them are multilayer networks downloaded from public repository (two of them
being Twitter networks). The results indicate that various state of the art
seed selection strategies for single-layer networks like K-Shell or VoteRank do
not perform so well on multilayer networks and are outperformed by Degree
Centrality
Distance-generalized Core Decomposition
The -core of a graph is defined as the maximal subgraph in which every
vertex is connected to at least other vertices within that subgraph. In
this work we introduce a distance-based generalization of the notion of
-core, which we refer to as the -core, i.e., the maximal subgraph in
which every vertex has at least other vertices at distance within
that subgraph. We study the properties of the -core showing that it
preserves many of the nice features of the classic core decomposition (e.g.,
its connection with the notion of distance-generalized chromatic number) and it
preserves its usefulness to speed-up or approximate distance-generalized
notions of dense structures, such as -club.
Computing the distance-generalized core decomposition over large networks is
intrinsically complex. However, by exploiting clever upper and lower bounds we
can partition the computation in a set of totally independent subcomputations,
opening the door to top-down exploration and to multithreading, and thus
achieving an efficient algorithm
Singularities in ternary mixtures of k-core percolation
Heterogeneous k-core percolation is an extension of a percolation model which
has interesting applications to the resilience of networks under random damage.
In this model, the notion of node robustness is local, instead of global as in
uniform k-core percolation. One of the advantages of k-core percolation models
is the validity of an analytical mathematical framework for a large class of
network topologies. We study ternary mixtures of node types in random networks
and show the presence of a new type of critical phenomenon. This scenario may
have useful applications in the stability of large scale infrastructures and
the description of glass-forming systems.Comment: To appear in Complex Networks, Studies in Computational Intelligence,
Proceedings of CompleNet 201
The evolution of interdisciplinarity in physics research
Science, being a social enterprise, is subject to fragmentation into groups
that focus on specialized areas or topics. Often new advances occur through
cross-fertilization of ideas between sub-fields that otherwise have little
overlap as they study dissimilar phenomena using different techniques. Thus to
explore the nature and dynamics of scientific progress one needs to consider
the large-scale organization and interactions between different subject areas.
Here, we study the relationships between the sub-fields of Physics using the
Physics and Astronomy Classification Scheme (PACS) codes employed for
self-categorization of articles published over the past 25 years (1985-2009).
We observe a clear trend towards increasing interactions between the different
sub-fields. The network of sub-fields also exhibits core-periphery
organization, the nucleus being dominated by Condensed Matter and General
Physics. However, over time Interdisciplinary Physics is steadily increasing
its share in the network core, reflecting a shift in the overall trend of
Physics research.Comment: Published version, 10 pages, 8 figures + Supplementary Informatio
СУЧАСНІ МЕТОДИ ФІЗИЧНОЇ РЕАБІЛІТАЦІЇ ХВОРИХ ПІСЛЯ АРТРОСКОПІЧНОЇ РЕКОНСТРУКЦІЇ ПЕРЕДНЬОЇ ХРЕСТОПОДІБНОЇ ЗВ’ЯЗКИ КОЛІННОГО СУГЛОБА
The article represents basic principles of application of methods of rehabilitation treatment in patients with the damage of the anterior cruciate ligament of the knee-joint. The deep analysis of scientific literary sources is conducted in relation to the disease course. Considerable attention is paid to the methodology of physical rehabilitation in pre- and postoperative periods.У статті висвітлено основні принципи застосування методів реабілітаційного лікування хворих з ушкодженням хрестоподібної зв’язки колінного суглоба. Проведено поглиблений аналіз наукових літературних джерел стосовно перебігу цього захворювання. Значну увагу приділено методології проведення фізичної реабілітації доопераційного та післяопераційного періодів
ПРИНЦИПИ ФІЗИЧНОЇ РЕАБІЛІТАЦІЇ ХВОРИХ іЗ ТРАВМОЮ КОЛІННОГО СУГЛОБА ПІСЛЯ проведення АРТРОСКОПІЧНОГО ОПЕРАційНОГО ВТРУЧАННЯ.
The article describes main principles of physical rehabilitation methods for patients with traumatic injury of the knee joint after arthroscopic surgery. Considerable attention is paid to the definition of the program of physical rehabilitation, which is aimed to reduce postoperative complications and restore functional capacity of the injured joint.У статті висвітлено основні принципи застосування методів фізичної реабілітації хворих із травматичним ушкодженням колінного суглоба після проведення артроскопічного втручання. Значну увагу приділено визначенню програми фізичної реабілітації, яка спрямована на зниження післяопераційних ускладнень та відновлення функціональної здатності ушкодженого суглоба
Hyperbolic Geometry of Complex Networks
We develop a geometric framework to study the structure and function of
complex networks. We assume that hyperbolic geometry underlies these networks,
and we show that with this assumption, heterogeneous degree distributions and
strong clustering in complex networks emerge naturally as simple reflections of
the negative curvature and metric property of the underlying hyperbolic
geometry. Conversely, we show that if a network has some metric structure, and
if the network degree distribution is heterogeneous, then the network has an
effective hyperbolic geometry underneath. We then establish a mapping between
our geometric framework and statistical mechanics of complex networks. This
mapping interprets edges in a network as non-interacting fermions whose
energies are hyperbolic distances between nodes, while the auxiliary fields
coupled to edges are linear functions of these energies or distances. The
geometric network ensemble subsumes the standard configuration model and
classical random graphs as two limiting cases with degenerate geometric
structures. Finally, we show that targeted transport processes without global
topology knowledge, made possible by our geometric framework, are maximally
efficient, according to all efficiency measures, in networks with strongest
heterogeneity and clustering, and that this efficiency is remarkably robust
with respect to even catastrophic disturbances and damages to the network
structure
Worldwide spreading of economic crisis
We model the spreading of a crisis by constructing a global economic network
and applying the Susceptible-Infected-Recovered (SIR) epidemic model with a
variable probability of infection. The probability of infection depends on the
strength of economic relations between the pair of countries, and the strength
of the target country. It is expected that a crisis which originates in a large
country, such as the USA, has the potential to spread globally, like the recent
crisis. Surprisingly we show that also countries with much lower GDP, such as
Belgium, are able to initiate a global crisis. Using the {\it k}-shell
decomposition method to quantify the spreading power (of a node), we obtain a
measure of ``centrality'' as a spreader of each country in the economic
network. We thus rank the different countries according to the shell they
belong to, and find the 12 most central countries. These countries are the most
likely to spread a crisis globally. Of these 12 only six are large economies,
while the other six are medium/small ones, a result that could not have been
otherwise anticipated. Furthermore, we use our model to predict the crisis
spreading potential of countries belonging to different shells according to the
crisis magnitude.Comment: 13 pages, 4 figures and Supplementary Materia
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