20,264 research outputs found
Multiphase smoothed-particle hydrodynamics
We adapt the smoothed-particle hydrodynamics (SPH) technique to allow a multiphase fluid in which SPH particles of widely differing density may be freely intermixed. Applications include modelling of galaxy formation and cooling flows
Capacity of a Simple Intercellular Signal Transduction Channel
We model the ligand-receptor molecular communication channel with a
discrete-time Markov model, and show how to obtain the capacity of this
channel. We show that the capacity-achieving input distribution is iid;
further, unusually for a channel with memory, we show that feedback does not
increase the capacity of this channel.Comment: 5 pages, 1 figure. To appear in the 2013 IEEE International Symposium
on Information Theor
A note on higher-dimensional magic matrices
We provide exact and asymptotic formulae for the number of unrestricted,
respectively indecomposable, -dimensional matrices where the sum of all
matrix entries with one coordinate fixed equals 2.Comment: AmS-LaTeX, 9 page
Finite-State Channel Models for Signal Transduction in Neural Systems
Information theory provides powerful tools for understanding communication
systems. This analysis can be applied to intercellular signal transduction,
which is a means of chemical communication among cells and microbes. We discuss
how to apply information-theoretic analysis to ligand-receptor systems, which
form the signal carrier and receiver in intercellular signal transduction
channels. We also discuss the applications of these results to neuroscience.Comment: Accepted for publication in 2016 IEEE International Conference on
Acoustics, Speech, and Signal Processing, Shanghai, Chin
Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation
We include a generalized infinite class of quark-gluon vertex dressing
diagrams in a study of how dynamics beyond the ladder-rainbow truncation
influences the Bethe-Salpeter description of light quark pseudoscalar and
vector mesons. The diagrammatic specification of the vertex is mapped into a
corresponding specification of the Bethe-Salpeter kernel, which preserves
chiral symmetry. This study adopts the algebraic format afforded by the simple
interaction kernel used in previous work on this topic. The new feature of the
present work is that in every diagram summed for the vertex and the
corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be
the self-consistent vertex solution. We also adopt from previous work the
effective accounting for the role of the explicitly non-Abelian three gluon
coupling in a global manner through one parameter determined from recent
lattice-QCD data for the vertex. With the more consistent vertex used here, the
error in ladder-rainbow truncation for vector mesons is never more than 10% as
the current quark mass is varied from the u/d region to the b region.Comment: 15 pages, 12 figure
Cytokines of Birds: Conserved Functions
Targeted disruptions of the mouse genes for cytokines, cytokine receptors, or components of cytokine signaling cascades convincingly revealed the important roles of these molecules in immunologic processes. Cytokines are used at present as drugs to fight chronic microbial infections and cancer in humans, and they are being evaluated as immune response modifiers to improve vaccines. Until recently, only a few avian cytokines have been characterized, and potential applications thus have remained limited to mammals. Classic approaches to identify cytokine genes in birds proved difficult because sequence conservation is generally low. As new technology and high throughput sequencing became available, this situation changed quickly. We review here recent work that led to the identification of genes for the avian homologs of interferon-a/b (IFNa/b) and IFN-g, various interleukins (IL), and several chemokines. From the initial data on the biochemical properties of these molecules, a picture is emerging that shows that avian and mammalian cytokines may perform similar tasks, although their primary structures in most cases are remarkably different
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