2,703 research outputs found
The Maxwell-Bloch Theory in Quantum Optics and the Kondo Model
In this letter, the problem of radiation in a fiber geometry interacting with
a two level atom is mapped onto the anisotropic Kondo model. Thermodynamical
and dynamical properties are then computed exploiting the integrability of this
latter system. We compute some correlation functions, decay rates and Lamb
shifts. In turn this leads to an analysis of the classical limit of the
anisotropic Kondo model.Comment: 4 pages, 1 figure. In Latex. Uses Revte
Laughlin's wave functions, Coulomb gases and expansions of the discriminant
In the context of the fractional quantum Hall effect, we investigate
Laughlin's celebrated ansatz for the groud state wave function at fractional
filling of the lowest Landau level. Interpreting its normalization in terms of
a one component plasma, we find the effect of an additional quadrupolar field
on the free energy, and derive estimates for the thermodynamically equivalent
spherical plasma. In a second part, we present various methods for expanding
the wave function in terms of Slater determinants, and obtain sum rules for the
coefficients. We also address the apparently simpler question of counting the
number of such Slater states using the theory of integral polytopes.Comment: 97 pages, using harvmac (with big option recommended) and epsf, 7
figures available upon request, Saclay preprint Spht 93/12
The potential of Antheraea pernyi silk for spinal cord repair
This work was supported by the Institute of Medical Sciences of the University of Aberdeen, Scottish Rugby Union and RS McDonald Charitable Trust. We are grateful to Mr Nicholas Hawkins from Oxford University and Ms Annette Raffan from the University of Aberdeen for assistance with tensile testing. We thank Ms Michelle Gniβ for her help with the microglial response experiments. We also thank Mr Gianluca Limodio for assisting with the MATLAB script for automation of tensile testing’s data analysis.Peer reviewedPublisher PD
The long delayed solution of the Bukhvostov Lipatov model
In this paper I complete the solution of the Bukhvostov Lipatov model by
computing the physical excitations and their factorized S matrix. I also
explain the paradoxes which led in recent years to the suspicion that the model
may not be integrable.Comment: 9 page
Correlations in one dimensional quantum impurity problems with an external field
We study response functions of integrable quantum impurity problems with an
external field at using non perturbative techniques derived from the
Bethe ansatz. We develop the first steps of the theory of excitations over the
new, field dependent ground state, leading to renormalized (or ``dressed'')
form-factors. We obtain exactly the low frequency behaviour of the dynamical
susceptibility in the double well problem of dissipative
quantum mechanics (or equivalently the anisotropic Kondo problem),and the low
frequency behaviour of the AC noise for tunneling between edges
in fractional quantum Hall devices. We also obtain exactly the structure of
singularities in and . Our results differ
significantly from previous perturbative approaches.Comment: harvmac, epsf, 37pgs, 2figs. modified some reference
Topo-Geometric Filtration Scheme for Geometric Active Contours and Level Sets: Application to Cerebrovascular Segmentation
One of the main problems of the existing methods for the
segmentation of cerebral vasculature is the appearance in the segmentation
result of wrong topological artefacts such as the kissing vessels.
In this paper, a new approach for the detection and correction of such
errors is presented. The proposed technique combines robust topological
information given by Persistent Homology with complementary geometrical
information of the vascular tree. The method was evaluated on 20
images depicting cerebral arteries. Detection and correction success rates
were 81.80% and 68.77%, respectively
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