32,486 research outputs found
Effects of growth factors and receptor blockade on gastrointestinal cancer
The advent of recombinant peptide technology offers the potential to use one or several peptides to treat a variety of gastrointestinal conditions. However, although cell culture and animal models have shown proof of concept, we are still at a relatively early stage in translating their use to standard clinical practice. Similarly, peptide and non-peptide antagonists of growth factor receptors show great potential as novel antichemotherapy agents. However, their actual place in clinical practice has yet to be established
Criticality of tuning in athermal phase transitions
We experimentally address the importance of tuning in athermal phase
transitions, which are triggered only by a slowly varying external field acting
as tuning parameter. Using higher order statistics of fluctuations, a singular
critical instability is detected for the first time in spite of an apparent
universal self-similar kinetics over a broad range of driving force. The
results as well as the experimental technique are likely to be of significance
to many slowly driven non-equilibrium systems from geophysics to material
science which display avalanche dynamics.Comment: 5 pages, 4 figure
Planar Two-particle Coulomb Interaction: Classical and Quantum Aspects
The classical and quantum aspects of planar Coulomb interactions have been
studied in detail. In the classical scenario, Action Angle Variables are
introduced to handle relativistic corrections, in the scheme of
time-independent perturbation theory. Complications arising due to the
logarithmic nature of the potential are pointed out. In the quantum case,
harmonic oscillator approximations are considered and effects of the
perturbations on the excited (oscillator) states have been analysed. In both
the above cases, the known 3+1-dimensional analysis is carried through side by
side, for a comparison with the 2+1-dimensional (planar) results.Comment: LaTex, Figures on request, e-mail:<[email protected]
A Parameterized Centrality Metric for Network Analysis
A variety of metrics have been proposed to measure the relative importance of
nodes in a network. One of these, alpha-centrality [Bonacich, 2001], measures
the number of attenuated paths that exist between nodes. We introduce a
normalized version of this metric and use it to study network structure,
specifically, to rank nodes and find community structure of the network.
Specifically, we extend the modularity-maximization method [Newman and Girvan,
2004] for community detection to use this metric as the measure of node
connectivity. Normalized alpha-centrality is a powerful tool for network
analysis, since it contains a tunable parameter that sets the length scale of
interactions. By studying how rankings and discovered communities change when
this parameter is varied allows us to identify locally and globally important
nodes and structures. We apply the proposed method to several benchmark
networks and show that it leads to better insight into network structure than
alternative methods.Comment: 11 pages, submitted to Physical Review
The role of the equation of state and the space-time dimension in spherical collapse
We study the spherically symmetric collapse of a fluid with non-vanishing
radial pressure in higher dimensional space-time. We obtain the general exact
solution in the closed form for the equation of state ()
which leads to the explicit construction of the root equation governing the
nature (black hole versus naked singularity) of the central singularity. A
remarkable feature of the root equation is its invariance for the three cases:
(),
() and () where is the
dimension of space-time. That is, for the ultimate end result of the collapse,
-dimensional dust, - AdS (anti de Sitter)-like and - dS-like
are absolutely equivalent.Comment: 4 Pages, RevTeX, no figures, minor changes, new references added,
Detailed version to follo
Probing electronic excitations in molecular conduction
We identify experimental signatures in the current-voltage (I-V)
characteristics of weakly contacted molecules directly arising from excitations
in their many electron spectrum. The current is calculated using a
multielectron master equation in the Fock space of an exact diagonalized model
many-body Hamiltonian for a prototypical molecule. Using this approach, we
explain several nontrivial features in frequently observed I-Vs in terms of a
rich spectrum of excitations that may be hard to describe adequately with
standard one-electron self-consistent field (SCF) theories.Comment: Significantly different content -- inadequacy of SCF approach
described with simple model, and a whole new class of experiments showing
gate modulated current steps discussed in terms of excitations in the
molecular many-body spac
A Characterization of Visibility Graphs for Pseudo-Polygons
In this paper, we give a characterization of the visibility graphs of
pseudo-polygons. We first identify some key combinatorial properties of
pseudo-polygons, and we then give a set of five necessary conditions based off
our identified properties. We then prove that these necessary conditions are
also sufficient via a reduction to a characterization of vertex-edge visibility
graphs given by O'Rourke and Streinu
Comment on ''Understanding the Area Proposal for Extremal Black Hole Entropy''
A. Ghosh and P. Mitra made the proposal how to explain the area law for the
entropy of extreme black holes in some model calculations. I argue that their
approach implicitly operates with strongly singular geometries and says nothing
about the contribution of regular metrics of extreme black holes into the
partition function.Comment: 5 pages, ReVTeX, no figures. Expanded from the journal version to
include response to Ghosh and Mitra Reply
Impact of Hall effect on energy decay in magnetohydrodynamic turbulence
We examine numerically the influence of Hall effect corrections to Ohm's law upon the decay of homogeneous compressible magnetohydrodynamic turbulence and conclude that there are no significant differences in global decay rate associated with the Hall effect. This affirms expectations that energy decay is controlled by the large-scale eddies
Lost equivalence of nonlinear sigma and models on noncommutative space
We show that the equivalence of nonlinear sigma and models which is
valid on the commutative space is broken on the noncommutative space. This
conclusion is arrived at through investigation of new BPS solitons that do not
exist in the commutative limit.Comment: 17 pages, LaTeX2
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