15,398 research outputs found
Metrics and isospectral partners for the most generic cubic PT-symmetric non-Hermitian Hamiltonian
We investigate properties of the most general PT-symmetric non-Hermitian
Hamiltonian of cubic order in the annihilation and creation operators as a ten
parameter family. For various choices of the parameters we systematically
construct an exact expression for a metric operator and an isospectral
Hermitian counterpart in the same similarity class by exploiting the
isomorphism between operator and Moyal products. We elaborate on the subtleties
of this approach. For special choices of the ten parameters the Hamiltonian
reduces to various models previously studied, such as to the complex cubic
potential, the so-called Swanson Hamiltonian or the transformed version of the
from below unbounded quartic -x^4-potential. In addition, it also reduces to
various models not considered in the present context, namely the single site
lattice Reggeon model and a transformed version of the massive sextic
x^6-potential, which plays an important role as a toy modelto identify theories
with vanishing cosmological constant.Comment: 21 page
Mechanical and microscopic properties of the reversible plastic regime in a 2D jammed material
At the microscopic level, plastic flow of a jammed, disordered material
consists of a series of particle rearrangements that cannot be reversed by
subsequent deformation. An infinitesimal deformation of the same material has
no rearrangements. Yet between these limits, there may be a self-organized
plastic regime with rearrangements, but with no net change upon reversing a
deformation. We measure the oscillatory response of a jammed interfacial
material, and directly observe rearrangements that couple to bulk stress and
dissipate energy, but do not always give rise to global irreversibility.Comment: 5 pages, 4 figures. A supplemental PDF detailing methods, and movies
corresponding to Fig. 2(a, b, f), are availabl
Subfactor realisation of modular invariants
We study the problem of realising modular invariants by braided subfactors
and the related problem of classifying nimreps. We develop the fusion rule
structure of these modular invariants. This structure is useful tool in the
analysis of modular data from quantum double subfactors, particularly those of
the double of cyclic groups, the symmetric group on 3 letters and the double of
the subfactors with principal graph the extended Dynkin diagram D_5^(1). In
particular for the double of S_3, 14 of the 48 modular modular invariants are
nimless, and only 28 of the remaining 34 nimble invariants can be realised by
subfactors
A Non-Parametric Learning Approach to Identify Online Human Trafficking
Human trafficking is among the most challenging law enforcement problems
which demands persistent fight against from all over the globe. In this study,
we leverage readily available data from the website "Backpage"-- used for
classified advertisement-- to discern potential patterns of human trafficking
activities which manifest online and identify most likely trafficking related
advertisements. Due to the lack of ground truth, we rely on two human analysts
--one human trafficking victim survivor and one from law enforcement, for
hand-labeling the small portion of the crawled data. We then present a
semi-supervised learning approach that is trained on the available labeled and
unlabeled data and evaluated on unseen data with further verification of
experts.Comment: Accepted in IEEE Intelligence and Security Informatics 2016
Conference (ISI 2016
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