68,889 research outputs found
Structure and evolution of a European Parliament via a network and correlation analysis
We present a study of the network of relationships among elected members of
the Finnish parliament, based on a quantitative analysis of initiative
co-signatures, and its evolution over 16 years. To understand the structure of
the parliament, we constructed a statistically validated network of members,
based on the similarity between the patterns of initiatives they signed. We
looked for communities within the network and characterized them in terms of
members' attributes, such as electoral district and party. To gain insight on
the nested structure of communities, we constructed a hierarchical tree of
members from the correlation matrix. Afterwards, we studied parliament dynamics
yearly, with a focus on correlations within and between parties, by also
distinguishing between government and opposition. Finally, we investigated the
role played by specific individuals, at a local level. In particular, whether
they act as proponents who gather consensus, or as signers. Our results provide
a quantitative background to current theories in political science. From a
methodological point of view, our network approach has proven able to highlight
both local and global features of a complex social system.Comment: 15 pages, 10 figure
Evolution of the social network of scientific collaborations
The co-authorship network of scientists represents a prototype of complex
evolving networks.
By mapping the electronic database containing all relevant journals in
mathematics and neuro-science for an eight-year period (1991-98), we infer the
dynamic and the structural mechanisms that govern the evolution and topology of
this complex system.
First, empirical measurements allow us to uncover the topological measures
that characterize the network at a given moment, as well as the time evolution
of these quantities.
The results indicate that the network is scale-free, and that the network
evolution is governed by preferential attachment, affecting both internal and
external links.
However, in contrast with most model predictions the average degree increases
in time, and the node separation decreases.
Second, we propose a simple model that captures the network's time evolution.
Third, numerical simulations are used to uncover the behavior of quantities
that could not be predicted analytically.Comment: 14 pages, 15 figure
Interplay between network structure and self-organized criticality
We investigate, by numerical simulations, how the avalanche dynamics of the
Bak-Tang-Wiesenfeld (BTW) sandpile model can induce emergence of scale-free
(SF) networks and how this emerging structure affects dynamics of the system.
We also discuss how the observed phenomenon can be used to explain evolution of
scientific collaboration.Comment: 4 pages, 4 figure
How are topics born? Understanding the research dynamics preceding the emergence of new areas
The ability to promptly recognise new research trends is strategic for many stake- holders, including universities, institutional funding bodies, academic publishers and companies. While the literature describes several approaches which aim to identify the emergence of new research topics early in their lifecycle, these rely on the assumption that the topic in question is already associated with a number of publications and consistently referred to by a community of researchers. Hence, detecting the emergence of a new research area at an embryonic stage, i.e., before the topic has been consistently labelled by a community of researchers and associated with a number of publications, is still an open challenge. In this paper, we begin to address this challenge by performing a study of the dynamics preceding the creation of new topics. This study indicates that the emergence of a new topic is anticipated by a significant increase in the pace of collaboration between relevant research areas, which can be seen as the ‘parents’ of the new topic. These initial findings (i) confirm our hypothesis that it is possible in principle to detect the emergence of a new topic at the embryonic stage, (ii) provide new empirical evidence supporting relevant theories in Philosophy of Science, and also (iii) suggest that new topics tend to emerge in an environment in which weakly interconnected research areas begin to cross-fertilise
Characterizing Interdisciplinarity of Researchers and Research Topics Using Web Search Engines
Researchers' networks have been subject to active modeling and analysis.
Earlier literature mostly focused on citation or co-authorship networks
reconstructed from annotated scientific publication databases, which have
several limitations. Recently, general-purpose web search engines have also
been utilized to collect information about social networks. Here we
reconstructed, using web search engines, a network representing the relatedness
of researchers to their peers as well as to various research topics.
Relatedness between researchers and research topics was characterized by
visibility boost-increase of a researcher's visibility by focusing on a
particular topic. It was observed that researchers who had high visibility
boosts by the same research topic tended to be close to each other in their
network. We calculated correlations between visibility boosts by research
topics and researchers' interdisciplinarity at individual level (diversity of
topics related to the researcher) and at social level (his/her centrality in
the researchers' network). We found that visibility boosts by certain research
topics were positively correlated with researchers' individual-level
interdisciplinarity despite their negative correlations with the general
popularity of researchers. It was also found that visibility boosts by
network-related topics had positive correlations with researchers' social-level
interdisciplinarity. Research topics' correlations with researchers'
individual- and social-level interdisciplinarities were found to be nearly
independent from each other. These findings suggest that the notion of
"interdisciplinarity" of a researcher should be understood as a
multi-dimensional concept that should be evaluated using multiple assessment
means.Comment: 20 pages, 7 figures. Accepted for publication in PLoS On
Enhanced solar anti-neutrino flux in random magnetic fields
We discuss the impact of the recent KamLAND constraint on the solar
anti-neutrino flux on the analysis of solar neutrino data in the presence of
Majorana neutrino transition magnetic moments and solar magnetic fields. We
consider different stationary solar magnetic field models, both regular and
random, highlighting the strong enhancement in the anti-neutrino production
rates that characterize turbulent solar magnetic field models. Moreover, we
show that for such magnetic fields inside the Sun, one can constrain the
intrinsic neutrino magnetic moment down to the level of mu_nu lessthan few
times 10^-12 x mu_B irrespective of details of the underlying turbulence model.
This limit is more stringent than all current experimental sensitivities, and
similar to the most stringent bounds obtained from stellar cooling. We also
comment on the robustness of this limit and show that at most it might be
weakened by one order of magnitude, under very unlikely circumstances.Comment: 25 pages, 5 figures; final version to appear in Phys. Rev.
Towards journalometrical analysis of a scientific periodical: a case study
In this paper we use several approaches to analyse a scientific journal as a
complex system and to make a possibly more complete description of its current
state and evolution. Methods of complex networks theory, statistics, and
queueing theory are used in this study. As a subject of the analysis we have
chosen the journal ``Condensed Matter Physics''
(http://www.icmp.lviv.ua/journal/). In particular, based on the statistical
data regarding the papers published in this journal since its foundation in
1993 up to now we have composed the co-authorship network and extracted its
main quantitative characteristics. Further, we analyse the priorities of
scientific trends reflected in the journal and its impact on the publications
in other editions (the citation ratings). Moreover, to characterize an
efficiency of the paper processing, we study the time dynamics of editorial
processing in terms of queueing theory and human activity analysis
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