1,729 research outputs found
Systems approaches and algorithms for discovery of combinatorial therapies
Effective therapy of complex diseases requires control of highly non-linear
complex networks that remain incompletely characterized. In particular, drug
intervention can be seen as control of signaling in cellular networks.
Identification of control parameters presents an extreme challenge due to the
combinatorial explosion of control possibilities in combination therapy and to
the incomplete knowledge of the systems biology of cells. In this review paper
we describe the main current and proposed approaches to the design of
combinatorial therapies, including the empirical methods used now by clinicians
and alternative approaches suggested recently by several authors. New
approaches for designing combinations arising from systems biology are
described. We discuss in special detail the design of algorithms that identify
optimal control parameters in cellular networks based on a quantitative
characterization of control landscapes, maximizing utilization of incomplete
knowledge of the state and structure of intracellular networks. The use of new
technology for high-throughput measurements is key to these new approaches to
combination therapy and essential for the characterization of control
landscapes and implementation of the algorithms. Combinatorial optimization in
medical therapy is also compared with the combinatorial optimization of
engineering and materials science and similarities and differences are
delineated.Comment: 25 page
Physical aspects of oracles for randomness, and Hadamard's conjecture
We analyze the physical aspects and origins of currently proposed oracles for
(absolute) randomness.Comment: 10 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:1405.140
Energy Dependence of the Delta Resonance: Chiral Dynamics in Action
There is an important connection between the low energy theorems of QCD and
the energy dependence of the Delta resonance in pi-N scattering, as well as the
closely related gamma^{*} N -> pi N reaction. The resonance shape is due not
only to the strong pi-N interaction in the p wave but the small interaction in
the s wave; the latter is due to spontaneous chiral symmetry breaking in QCD
(i.e. the Nambu-Goldstone nature of the pion). A brief overview of experimental
tests of chiral perturbation theory and chiral based models is presentedComment: 11 pages, 6 figures, Festschrift for S.N. yan
Iatrogenic ulnar nerve injury after pin fixation and after antegrade nailing of supracondylar humeral fractures in children
Majorana Zero-modes and Topological Phases of Multi-flavored Jackiw-Rebbi model
Motivated by the recent Kitaev's K-theory analysis of topological insulators
and superconductors, we adopt the same framework to study the topological phase
structure of Jackiw-Rebbi model in 3+1 dimensions. According to the K-theory
analysis based on the properties of the charge conjugation and time reversal
symmetries, we classify the topological phases of the model. In particular, we
find that there exist Majorana zero-modes hosted by the
hedgehogs/t'Hooft-Polyakov monopoles, if the model has a time reversal
symmetry. Guided by the K-theory results, we then explicitly show that a single
Majorana zero mode solution exists for the SU(2) doublet fermions in some
co-dimensional one planes of the mass parameter space. It turns out we can see
the existence of none or a single zero mode when the fermion doublet is only
two. We then take a step further to consider four-fermion case and find there
can be zero, one or two normalizable zero mode in some particular choices of
mass matrices. Our results also indicate that a single normalizable Majorana
zero mode can be compatible with the cancellation of SU(2) Witten anomaly.Comment: 29 pages, 3 figures; v2, typos correcte
Eikonal methods applied to gravitational scattering amplitudes
We apply factorization and eikonal methods from gauge theories to scattering
amplitudes in gravity. We hypothesize that these amplitudes factor into an
IR-divergent soft function and an IR-finite hard function, with the former
given by the expectation value of a product of gravitational Wilson line
operators. Using this approach, we show that the IR-divergent part of the
n-graviton scattering amplitude is given by the exponential of the one-loop IR
divergence, as originally discovered by Weinberg, with no additional subleading
IR-divergent contributions in dimensional regularization.Comment: 16 pages, 3 figures; v2: title change and minor rewording (published
version); v3: typos corrected in eqs.(3.2),(4.1
Spontaneous Parity Violation in SUSY Strong Gauge Theory
We suggest simple models of spontaneous parity violation in supersymmetric
strong gauge theory. We focus on left-right symmetric model and investigate
vacuum with spontaneous parity violation. Non-perturbative effects are
calculable in supersymmetric gauge theory, and we suggest two new models. The
first model shows confinement, and the second model has a dual description of
the theory. The left-right symmetry breaking and electroweak symmetry breaking
are simultaneously occurred with the suitable energy scale hierarchy. The
second model also induces spontaneous supersymmetry breaking.Comment: 14 page
Fluids in cosmology
We review the role of fluids in cosmology by first introducing them in
General Relativity and then by applying them to a FRW Universe's model. We
describe how relativistic and non-relativistic components evolve in the
background dynamics. We also introduce scalar fields to show that they are able
to yield an inflationary dynamics at very early times (inflation) and late
times (quintessence). Then, we proceed to study the thermodynamical properties
of the fluids and, lastly, its perturbed kinematics. We make emphasis in the
constrictions of parameters by recent cosmological probes.Comment: 34 pages, 4 figures, version accepted as invited review to the book
"Computational and Experimental Fluid Mechanics with Applications to Physics,
Engineering and the Environment". Version 2: typos corrected and references
expande
Analytic Results for Higgs Production in Bottom Fusion
We evaluate analytically the cross section for Higgs production plus one jet
through bottom quark fusion. By considering the small pT limit we derive
expressions for the resummation coefficients governing the structure of large
logarithms, and compare these expressions with those available in the
literature.Comment: 14 pages, 7 figure
Continuity, Deconfinement, and (Super) Yang-Mills Theory
We study the phase diagram of SU(2) Yang-Mills theory with one adjoint Weyl
fermion on R^3xS^1 as a function of the fermion mass m and the compactification
scale L. This theory reduces to thermal pure gauge theory as m->infinity and to
circle-compactified (non-thermal) supersymmetric gluodynamics in the limit
m->0. In the m-L plane, there is a line of center symmetry changing phase
transitions. In the limit m->infinity, this transition takes place at
L_c=1/T_c, where T_c is the critical temperature of the deconfinement
transition in pure Yang-Mills theory. We show that near m=0, the critical
compactification scale L_c can be computed using semi-classical methods and
that the transition is of second order. This suggests that the deconfining
phase transition in pure Yang-Mills theory is continuously connected to a
transition that can be studied at weak coupling. The center symmetry changing
phase transition arises from the competition of perturbative contributions and
monopole-instantons that destabilize the center, and topological molecules
(neutral bions) that stabilize the center. The contribution of molecules can be
computed using supersymmetry in the limit m=0, and via the
Bogomolnyi--Zinn-Justin (BZJ) prescription in the non-supersymmetric gauge
theory. Finally, we also give a detailed discussion of an issue that has not
received proper attention in the context of N=1 theories---the non-cancellation
of nonzero-mode determinants around supersymmetric BPS and KK
monopole-instanton backgrounds on R^3xS^1. We explain why the non-cancellation
is required for consistency with holomorphy and supersymmetry and perform an
explicit calculation of the one-loop determinant ratio.Comment: A discussion of the non-cancellation of the nonzero mode determinants
around supersymmetric monopole-instantons in N=1 SYM on R^3xS^1 is added,
including an explicit calculation. The non-cancellation is, in fact, required
by supersymmetry and holomorphy in order for the affine-Toda superpotential
to be reproduced. References have also been adde
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