493 research outputs found
A simple physical model for scaling in protein-protein interaction networks
It has recently been demonstrated that many biological networks exhibit a
scale-free topology where the probability of observing a node with a certain
number of edges (k) follows a power law: i.e. p(k) ~ k^-g. This observation has
been reproduced by evolutionary models. Here we consider the network of
protein-protein interactions and demonstrate that two published independent
measurements of these interactions produce graphs that are only weakly
correlated with one another despite their strikingly similar topology. We then
propose a physical model based on the fundamental principle that (de)solvation
is a major physical factor in protein-protein interactions. This model
reproduces not only the scale-free nature of such graphs but also a number of
higher-order correlations in these networks. A key support of the model is
provided by the discovery of a significant correlation between number of
interactions made by a protein and the fraction of hydrophobic residues on its
surface. The model presented in this paper represents the first physical model
for experimentally determined protein-protein interactions that comprehensively
reproduces the topological features of interaction networks. These results have
profound implications for understanding not only protein-protein interactions
but also other types of scale-free networks.Comment: 50 pages, 17 figure
Quasistatic Scale-free Networks
A network is formed using the sites of an one-dimensional lattice in the
shape of a ring as nodes and each node with the initial degree .
links are then introduced to this network, each link starts from a distinct
node, the other end being connected to any other node with degree randomly
selected with an attachment probability proportional to . Tuning
the control parameter we observe a transition where the average degree
of the largest node changes its variation from to
at a specific transition point of . The network is scale-free i.e.,
the nodal degree distribution has a power law decay for .Comment: 4 pages, 5 figure
Self-similar disk packings as model spatial scale-free networks
The network of contacts in space-filling disk packings, such as the
Apollonian packing, are examined. These networks provide an interesting example
of spatial scale-free networks, where the topology reflects the broad
distribution of disk areas. A wide variety of topological and spatial
properties of these systems are characterized. Their potential as models for
networks of connected minima on energy landscapes is discussed.Comment: 13 pages, 12 figures; some bugs fixed and further discussion of
higher-dimensional packing
WormBase 2007
WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences
Directly e-mailing authors of newly published papers encourages community curation
Much of the data within Model Organism Databases (MODs) comes from manual curation of the primary research literature. Given limited funding and an increasing density of published material, a significant challenge facing all MODs is how to efficiently and effectively prioritize the most relevant research papers for detailed curation. Here, we report recent improvements to the triaging process used by FlyBase. We describe an automated method to directly e-mail corresponding authors of new papers, requesting that they list the genes studied and indicate (‘flag’) the types of data described in the paper using an online tool. Based on the author-assigned flags, papers are then prioritized for detailed curation and channelled to appropriate curator teams for full data extraction. The overall response rate has been 44% and the flagging of data types by authors is sufficiently accurate for effective prioritization of papers. In summary, we have established a sustainable community curation program, with the result that FlyBase curators now spend less time triaging and can devote more effort to the specialized task of detailed data extraction
A Gene Wiki for Community Annotation of Gene Function
This manuscript describes the creation of comprehensive gene wiki, seeded with data from public domain sources, which will enable and encourage community annotation of gene function
Search for a dark vector gauge boson decaying to using decays
We report a search for a dark vector gauge boson that couples to
quarks in the decay chain , . No signal is found and we set a
mass-dependent limit on the baryonic fine structure constant of in the mass range of 290 to 520 MeV/. This analysis is
based on a data sample of 976 fb collected by the Belle experiment at
the KEKB asymmetric-energy collider.Comment: 6 pages, 4 figure
Search for decays to invisible final states at Belle
We report the result from the first search for decays to invisible
final states. The analysis is performed on a data sample of 924
collected at and near the and resonances with the
Belle detector at the KEKB asymmetric-energy collider. The
absolute branching fraction is determined using an inclusive sample,
obtained by fully reconstructing the rest of the particle system including the
other charmed particle. No significant signal yield is observed and an upper
limit of is set on the branching fraction of to
invisible final states at 90\% confidence level.Comment: 17 pages, 4 figures, submitted to PRD(RC
Statistical mechanics of complex networks
Complex networks describe a wide range of systems in nature and society, much
quoted examples including the cell, a network of chemicals linked by chemical
reactions, or the Internet, a network of routers and computers connected by
physical links. While traditionally these systems were modeled as random
graphs, it is increasingly recognized that the topology and evolution of real
networks is governed by robust organizing principles. Here we review the recent
advances in the field of complex networks, focusing on the statistical
mechanics of network topology and dynamics. After reviewing the empirical data
that motivated the recent interest in networks, we discuss the main models and
analytical tools, covering random graphs, small-world and scale-free networks,
as well as the interplay between topology and the network's robustness against
failures and attacks.Comment: 54 pages, submitted to Reviews of Modern Physic
- …