1,951 research outputs found
Effect of a second generation alpha2delta ligand, pregabalin on visceral sensation: a randomised controlled pilot study.
General Framework for phase synchronization through localized sets
We present an approach which enables to identify phase synchronization in
coupled chaotic oscillators without having to explicitly measure the phase. We
show that if one defines a typical event in one oscillator and then observes
another one whenever this event occurs, these observations give rise to a
localized set. Our result provides a general and easy way to identify PS, which
can also be used to oscillators that possess multiple time scales. We
illustrate our approach in networks of chemically coupled neurons. We show that
clusters of phase synchronous neurons may emerge before the onset of phase
synchronization in the whole network, producing a suitable environment for
information exchanging. Furthermore, we show the relation between the localized
sets and the amount of information that coupled chaotic oscillator can
exchange
On the Complex Network Structure of Musical Pieces: Analysis of Some Use Cases from Different Music Genres
This paper focuses on the modeling of musical melodies as networks. Notes of
a melody can be treated as nodes of a network. Connections are created whenever
notes are played in sequence. We analyze some main tracks coming from different
music genres, with melodies played using different musical instruments. We find
out that the considered networks are, in general, scale free networks and
exhibit the small world property. We measure the main metrics and assess
whether these networks can be considered as formed by sub-communities. Outcomes
confirm that peculiar features of the tracks can be extracted from this
analysis methodology. This approach can have an impact in several multimedia
applications such as music didactics, multimedia entertainment, and digital
music generation.Comment: accepted to Multimedia Tools and Applications, Springe
A Uniqueness Theorem for Constraint Quantization
This work addresses certain ambiguities in the Dirac approach to constrained
systems. Specifically, we investigate the space of so-called ``rigging maps''
associated with Refined Algebraic Quantization, a particular realization of the
Dirac scheme. Our main result is to provide a condition under which the rigging
map is unique, in which case we also show that it is given by group averaging
techniques. Our results comprise all cases where the gauge group is a
finite-dimensional Lie group.Comment: 23 pages, RevTeX, further comments and references added (May 26. '99
Systems biologists seek fuller integration of systems biology approaches in new cancer research programs
Systems biology takes an interdisciplinary approach to the systematic study of complex interactions in biological systems. This approach seeks to decipher the emergent behaviors of complex systems rather than focusing only on their constituent properties. As an increasing number of examples illustrate the value of systems biology approaches to understand the initiation, progression, and treatment of cancer, systems biologists from across Europe and the United States hope for changes in the way their field is currently perceived among cancer researchers. In a recent EU-US workshop, supported by the European Commission, the German Federal Ministry for Education and Research, and the National Cancer Institute of the NIH, the participants discussed the strengths, weaknesses, hurdles, and opportunities in cancer systems biology
QED theory of the nuclear recoil effect in atoms
The quantum electrodynamic theory of the nuclear recoil effect in atoms to
all orders in \alpha Z is formulated. The nuclear recoil corrections for atoms
with one and two electrons over closed shells are considered in detail. The
problem of the composite nuclear structure in the theory of the nuclear recoil
effect is discussed.Comment: 20 pages, 6 figures, Late
Edge overload breakdown in evolving networks
We investigate growing networks based on Barabasi and Albert's algorithm for
generating scale-free networks, but with edges sensitive to overload breakdown.
the load is defined through edge betweenness centrality. We focus on the
situation where the average number of connections per vertex is, as the number
of vertices, linearly increasing in time. After an initial stage of growth, the
network undergoes avalanching breakdowns to a fragmented state from which it
never recovers. This breakdown is much less violent if the growth is by random
rather than preferential attachment (as defines the Barabasi and Albert model).
We briefly discuss the case where the average number of connections per vertex
is constant. In this case no breakdown avalanches occur. Implications to the
growth of real-world communication networks are discussed.Comment: To appear in Phys. Rev.
A stochastic model for heart rate fluctuations
Normal human heart rate shows complex fluctuations in time, which is natural,
since heart rate is controlled by a large number of different feedback control
loops. These unpredictable fluctuations have been shown to display fractal
dynamics, long-term correlations, and 1/f noise. These characterizations are
statistical and they have been widely studied and used, but much less is known
about the detailed time evolution (dynamics) of the heart rate control
mechanism. Here we show that a simple one-dimensional Langevin-type stochastic
difference equation can accurately model the heart rate fluctuations in a time
scale from minutes to hours. The model consists of a deterministic nonlinear
part and a stochastic part typical to Gaussian noise, and both parts can be
directly determined from the measured heart rate data. Studies of 27 healthy
subjects reveal that in most cases the deterministic part has a form typically
seen in bistable systems: there are two stable fixed points and one unstable
one.Comment: 8 pages in PDF, Revtex style. Added more dat
Lethality and centrality in protein networks
In this paper we present the first mathematical analysis of the protein
interaction network found in the yeast, S. cerevisiae. We show that, (a) the
identified protein network display a characteristic scale-free topology that
demonstrate striking similarity to the inherent organization of metabolic
networks in particular, and to that of robust and error-tolerant networks in
general. (b) the likelihood that deletion of an individual gene product will
prove lethal for the yeast cell clearly correlates with the number of
interactions the protein has, meaning that highly-connected proteins are more
likely to prove essential than proteins with low number of links to other
proteins. These results suggest that a scale-free architecture is a generic
property of cellular networks attributable to universal self-organizing
principles of robust and error-tolerant networks and that will likely to
represent a generic topology for protein-protein interactions.Comment: See also http:/www.nd.edu/~networks and
http:/www.nd.edu/~networks/cel
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