2,787 research outputs found
Multisymplectic approach to integrable defects in the sine-Gordon model
Ideas from the theory of multisymplectic systems, introduced recently in integrable systems by the author and Kundu to discuss Liouville integrability in classical field theories with a defect, are applied to the sine-Gordon model. The key ingredient is the introduction of a second Poisson bracket in the theory that allows for a Hamiltonian description of the model that is completely equivalent to the standard one, in the absence of a defect. In the presence of a defect described by frozen Bäcklund transformations, our approach based on the new bracket unifies the various tools used so far to attack the problem. It also gets rid of the known issues related to the evaluation of the Poisson brackets of the defect matrix which involve fields at coinciding space point (the location of the defect). The original Lagrangian approach also finds a nice reinterpretation in terms of the canonical transformation representing the defect conditions
Interplay between Zamolodchikov-Faddeev and Reflection-Transmission algebras
We show that a suitable coset algebra, constructed in terms of an extension
of the Zamolodchikov-Faddeev algebra, is homomorphic to the
Reflection-Transmission algebra, as it appears in the study of integrable
systems with impurity.Comment: 8 pages; a misprint in eq. (2.14) and (2.15) has been correcte
Form factors of boundary fields for A(2)-affine Toda field theory
In this paper we carry out the boundary form factor program for the
A(2)-affine Toda field theory at the self-dual point. The latter is an
integrable model consisting of a pair of particles which are conjugated to each
other and possessing two bound states resulting from the scattering processes 1
+1 -> 2 and 2+2-> 1. We obtain solutions up to four particle form factors for
two families of fields which can be identified with spinless and spin-1 fields
of the bulk theory. Previously known as well as new bulk form factor solutions
are obtained as a particular limit of ours. Minimal solutions of the boundary
form factor equations for all A(n)-affine Toda field theories are given, which
will serve as starting point for a generalisation of our results to higher rank
algebras.Comment: 24 pages LaTeX, 1 figur
On Instantons and Zero Modes of N=1/2 SYM Theory
We study zero modes of N=1/2 supersymmetric Yang-Mills action in the
background of instantons. In this background, because of a quartic antichiral
fermionic term in the action, the fermionic solutions of the equations of
motion are not in general zero modes of the action. Hence, when there are
fermionic solutions, the action is no longer minimized by instantons. By
deforming the instanton equation in the presence of fermions, we write down the
zero mode equations. The solutions satisfy the equations of motion, and
saturate the BPS bound. The deformed instanton equations imply that the finite
action solutions have U(1) connections which are not flat anymore.Comment: 9 pages, latex file, added references, minor change
Toda Lattice Models with Boundary
We consider the soliton solutions in 1- and (1+1)-dimensional Toda lattice
models with a boundary. We make use of the solutions already known on a full
line by means of the Hirota's method. We explicitly construct the solutions
satisfying the boundary conditions. The -symmetric boundary
condition can be introduced by the two-soliton solutions naturally.Comment: 9 pages, latex, no figure
Non-Abelian Vortices, Super-Yang-Mills Theory and Spin(7)-Instantons
We consider a complex vector bundle E endowed with a connection A over the
eight-dimensional manifold R^2 x G/H, where G/H = SU(3)/U(1)xU(1) is a
homogeneous space provided with a never integrable almost complex structure and
a family of SU(3)-structures. We establish an equivalence between G-invariant
solutions A of the Spin(7)-instanton equations on R^2 x G/H and general
solutions of non-Abelian coupled vortex equations on R^2. These vortices are
BPS solitons in a d=4 gauge theory obtained from N=1 supersymmetric Yang-Mills
theory in ten dimensions compactified on the coset space G/H with an
SU(3)-structure. The novelty of the obtained vortex equations lies in the fact
that Higgs fields, defining morphisms of vector bundles over R^2, are not
holomorphic in the generic case. Finally, we introduce BPS vortex equations in
N=4 super Yang-Mills theory and show that they have the same feature.Comment: 14 pages; v2: typos fixed, published versio
Biologically modified microelectrode sensors provide enhanced sensitivity for detection of nucleic acid sequences from Mycobacterium tuberculosis
This paper describes improved sensitivity when using biosensors based on microfabricated microelectrodes to detect DNA, with the goal of progressing towards a low cost and mass manufacturable assay for antibiotic resistance in tuberculosis (TB). The microelectrodes gave a near 20 times improvement in sensitivity compared to polycrystalline macroelectrodes. In addition, experimental parameters such as redox mediator concentration and experimental technique were investigated and optimised. It was found that lower concentrations of redox mediator gave higher signal changes when measuring hybridisation events and, at these lower concentrations, square wave voltammetry was more sensitive and consistent than differential pulse voltammetry. Together, this paper presents a quantifiable comparison of macroelectrode and microelectrode DNA biosensors. The final assay demonstrates enhanced sensitivity through reduction of sensor size, reduction of redox mediator concentration and judicious choice of detection technique, therefore maintaining manufacturability for incorporation into point of care tests and lab-on-a-chip devices
Noncommutative U(1) Instantons in Eight Dimensional Yang-Mills Theory
We study the noncommutative version of the extended ADHM construction in the
eight dimensional U(1) Yang-Mills theory. This construction gives rise to the
solutions of the BPS equations in the Yang-Mills theory, and these solutions
preserve at least 3/16 of supersymmetries. In a wide subspace of the extended
ADHM data, we show that the integer which appears in the extended ADHM
construction should be interpreted as the -brane charge rather than the
-brane charge by explicitly calculating the topological charges in the case
that the noncommutativity parameter is anti-self-dual. We also find the
relationship with the solution generating technique and show that the integer
can be interpreted as the charge of the -brane bound to the -brane
with the -field in the case that the noncommutativity parameter is
self-dual.Comment: 22 page
Requirements and validation of a prototype learning health system for clinical diagnosis
Introduction Diagnostic error is a major threat to patient safety in the context of family practice. The patient safety implications are severe for both patient and clinician. Traditional approaches to diagnostic decision support have lacked broad acceptance for a number of well-documented reasons: poor integration with electronic health records and clinician workflow, static evidence that lacks transparency and trust, and use of proprietary technical standards hindering wider interoperability. The learning health system (LHS) provides a suitable infrastructure for development of a new breed of learning decision support tools. These tools exploit the potential for appropriate use of the growing volumes of aggregated sources of electronic health records. Methods We describe the experiences of the TRANSFoRm project developing a diagnostic decision support infrastructure consistent with the wider goals of the LHS. We describe an architecture that is model driven, service oriented, constructed using open standards, and supports evidence derived from electronic sources of patient data. We describe the architecture and implementation of 2 critical aspects for a successful LHS: the model representation and translation of clinical evidence into effective practice and the generation of curated clinical evidence that can be used to populate those models, thus closing the LHS loop. Results/Conclusions Six core design requirements for implementing a diagnostic LHS are identified and successfully implemented as part of this research work. A number of significant technical and policy challenges are identified for the LHS community to consider, and these are discussed in the context of evaluating this work: medico-legal responsibility for generated diagnostic evidence, developing trust in the LHS (particularly important from the perspective of decision support), and constraints imposed by clinical terminologies on evidence generation
Quantum corrections to static solutions of Nahm equation and Sin-Gordon models via generalized zeta-function
One-dimensional Yang-Mills Equations are considered from a point of view of a
class of nonlinear Klein-Gordon-Fock models. The case of self-dual Nahm
equations and non-self-dual models are discussed. A quasiclassical quantization
of the models is performed by means of generalized zeta-function and its
representation in terms of a Green function diagonal for a heat equation with
the correspondent potential. It is used to evaluate the functional integral and
quantum corrections to mass in the quasiclassical approximation.
Quantum corrections to a few periodic (and kink) solutions of the Nahm as a
particular case of the Ginzburg-Landau (phi-in-quadro) and and Sin-Gordon
models are evaluated in arbitrary dimensions. The Green function diagonal for
heat equation with a finite-gap potential is constructed by universal
description via solutions of Hermit equation. An alternative approach based on
Baker-Akhiezer functions for KP equation is proposed . The generalized
zeta-function and its derivative at zero point as the quantum corrections to
mass is expressed in terms of elliptic integrals.Comment: Workshop Nonlinear Physics and Experiment; Gallipoli, 200
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