3,744 research outputs found
On the internal consistency of short-term, medium-term and long-term oil price forecasts
Some protein interaction data do not exhibit power law statistics
It has been claimed that protein-protein interaction (PPI) networks are
scale-free based on the observation that the node degree sequence follows a
power law. Here we argue that these claims are likely to be based on erroneous
statistical analysis. Typically, the supporting data are presented using
frequency-degree plots. We show that such plots can be misleading, and should
correctly be replaced by rank-degree plots. We provide two PPI network examples
in which the frequency-degree plots appear linear on a log-log scale, but the
rank-degree plots demonstrate that the node degree sequence is far from a power
law. We conclude that at least these PPI networks are not scale-free.Comment: 4 pages, 2 figure
Graph theoretic analysis of protein interaction networks of eukaryotes
Thanks to recent progress in high-throughput experimental techniques, the
datasets of large-scale protein interactions of prototypical multicellular
species, the nematode worm Caenorhabditis elegans and the fruit fly Drosophila
melanogaster, have been assayed. The datasets are obtained mainly by using the
yeast hybrid method, which contains false-positive and false-negative
simultaneously. Accordingly, while it is desirable to test such datasets
through further wet experiments, here we invoke recent developed network theory
to test such high throughput datasets in a simple way. Based on the fact that
the key biological processes indispensable to maintaining life are universal
across eukaryotic species, and the comparison of structural properties of the
protein interaction networks (PINs) of the two species with those of the yeast
PIN, we find that while the worm and the yeast PIN datasets exhibit similar
structural properties, the current fly dataset, though most comprehensively
screened ever, does not reflect generic structural properties correctly as it
is. The modularity is suppressed and the connectivity correlation is lacking.
Addition of interlogs to the current fly dataset increases the modularity and
enhances the occurrence of triangular motifs as well. The connectivity
correlation function of the fly, however, remains distinct under such interlogs
addition, for which we present a possible scenario through an in silico
modeling.Comment: 7 pages, 6 figures, 2 table
Revival of the side-to-side approach for distal coronary anastomosis
Side-to-side anastomosis was employed by just ten proportional stitches while performing distal anastomosis during coronary artery surgery. This technique is simple and quick. Here this simple technique is described in detail and the postoperative status of grafted conduits is reported
Haptic Device System for Upper Limb and Cognitive Rehabilitation â Application for Development Disorder Children
Understanding and Predicting Protein Assemblies With 3D Structures
Protein interactions are central to most biological processes, and are currently the subject of great interest. Yet despite the many recently developed methods for
interaction discovery, little attention has been paid to one of the best sources of
data: complexes of known three-dimensional (3D) structure. Here we discuss how
such complexes can be used to study and predict protein interactions and complexes,
and to interrogate interaction networks proposed by methods such as two-hybrid
screens or affinity purifications
Large-scale inference and graph theoretical analysis of gene-regulatory networks in B. stubtilis
We present the methods and results of a two-stage modeling process that
generates candidate gene-regulatory networks of the bacterium B. subtilis from
experimentally obtained, yet mathematically underdetermined microchip array
data. By employing a computational, linear correlative procedure to generate
these networks, and by analyzing the networks from a graph theoretical
perspective, we are able to verify the biological viability of our inferred
networks, and we demonstrate that our networks' graph theoretical properties
are remarkably similar to those of other biological systems. In addition, by
comparing our inferred networks to those of a previous, noisier implementation
of the linear inference process [17], we are able to identify trends in graph
theoretical behavior that occur both in our networks as well as in their
perturbed counterparts. These commonalities in behavior at multiple levels of
complexity allow us to ascertain the level of complexity to which our process
is robust to noise.Comment: 22 pages, 4 figures, accepted for publication in Physica A (2006
Hyperbolic Space Cosmologies
We present a systematic study of accelerating cosmologies obtained from
M/string theory compactifications of hyperbolic spaces with time-varying
volume. A set of vacuum solutions where the internal space is a product of
hyperbolic manifolds is found to give qualitatively the same accelerating
four-dimensional FLRW universe behavior as a single hyperbolic space. We also
examine the possibility that our universe is a hyperbolic space and provide
exact Milne type solutions, as well as intersecting S-brane solutions. When
both the usual 4D spacetime and the m-dimensional internal space are
hyperbolic, we find eternally accelerating cosmologies for , with and
without form field backgrounds. In particular, the effective potential for a
magnetic field background in the large 3 dimensions is positive definite with a
local minimum and thus enhances the eternally accelerating expansion.Comment: 33 pages, 2 figures; v2 refs added; v3 minor change in text, JHEP
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