12,142 research outputs found
Dressing approach to the nonvanishing boundary value problem for the AKNS hierarchy
We propose an approach to the nonvanishing boundary value problem for
integrable hierarchies based on the dressing method. Then we apply the method
to the AKNS hierarchy. The solutions are found by introducing appropriate
vertex operators that takes into account the boundary conditions.Comment: Published version Proc. Quantum Theory and Symmetries 7
(QTS7)(Prague, Czech Republic, 2011
Conceptual inconsistencies in finite-dimensional quantum and classical mechanics
Utilizing operational dynamic modeling [Phys. Rev. Lett. 109, 190403 (2012);
arXiv:1105.4014], we demonstrate that any finite-dimensional representation of
quantum and classical dynamics violates the Ehrenfest theorems. Other
peculiarities are also revealed, including the nonexistence of the free
particle and ambiguity in defining potential forces. Non-Hermitian mechanics is
shown to have the same problems. This work compromises a popular belief that
finite-dimensional mechanics is a straightforward discretization of the
corresponding infinite-dimensional formulation.Comment: 5 pages, 2 figure
Beyond conventional factorization: Non-Hermitian Hamiltonians with radial oscillator spectrum
The eigenvalue problem of the spherically symmetric oscillator Hamiltonian is
revisited in the context of canonical raising and lowering operators. The
Hamiltonian is then factorized in terms of two not mutually adjoint factorizing
operators which, in turn, give rise to a non-Hermitian radial Hamiltonian. The
set of eigenvalues of this new Hamiltonian is exactly the same as the energy
spectrum of the radial oscillator and the new square-integrable eigenfunctions
are complex Darboux-deformations of the associated Laguerre polynomials.Comment: 13 pages, 7 figure
On negative flows of the AKNS hierarchy and a class of deformations of bihamiltonian structure of hydrodynamic type
A deformation parameter of a bihamiltonian structure of hydrodynamic type is
shown to parameterize different extensions of the AKNS hierarchy to include
negative flows. This construction establishes a purely algebraic link between,
on the one hand, two realizations of the first negative flow of the AKNS model
and, on the other, two-component generalizations of Camassa-Holm and Dym type
equations.
The two-component generalizations of Camassa-Holm and Dym type equations can
be obtained from the negative order Hamiltonians constructed from the Lenard
relations recursively applied on the Casimir of the first Poisson bracket of
hydrodynamic type. The positive order Hamiltonians, which follow from Lenard
scheme applied on the Casimir of the second Poisson bracket of hydrodynamic
type, are shown to coincide with the Hamiltonians of the AKNS model. The AKNS
Hamiltonians give rise to charges conserved with respect to equations of motion
of two-component Camassa-Holm and two-component Dym type equations.Comment: 20 pages, Late
Solid cancers after antiplatelet therapy: Confirmations, controversies, and challenges
© Schattauer 2015. The role of anticoagulants and antiplatelet agents in tumour growth and prognosis is not new, and currently under intense investigation. Some randomised data strongly suggest that this association exists, but it is complex, and not necessarily pointed at the same direction. The potential mechanisms responsible for such harmful association include a direct hazard of novel antithrombotics on cancer, indirect promotion of tumour growth, easier metastatic dissemination due to instability of platelet-tumour cell aggregates, or/and inability to keep cancer cells locally in situ are considered. The latest randomised evidence ultimately rejected the drug-specific cancer risks, clearly indicating the class-effect. In lay terms “cancers follow bleeding”, which seems to be true for antithrombotic agents in general. Significant excess of solid cancers which was similar after prasugrel in TRITON, and with vorapaxar in TRACER trials was confirmed by the FDA reviews. Later, extra cancer deaths reported following clopidogrel and prasugrel in DAPT, and after ticagrelor in PEGASUS are also of concern. However, there are remaining controversies with regard to published cancer risks after ticagrelor (PLATO), or another vorapaxar trial (TRA2P), while full disclosure of separate clopidogrel and prasugrel cancer data in DAPT is still lacking. In short, if we apply moderate antiplatelet strategies for over two years, or aggressive regimens including triple therapy for much less than one year, the solid cancer risks emerge. Currently, more delicate platelet inhibition, and shorter exposure to dual oral antiplatelet agents should prevail
The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals
We present the waveform digitiser used in the Double Chooz experiment. We
describe the hardware and the custom-built firmware specifically developed for
the experiment. The performance of the device is tested with regards to
digitising low light level signals from photomultiplier tubes and measuring
pulse charge. This highlights the role of quantisation effects and leads to
some general recommendations on the design and use of waveform digitisers.Comment: 14 pages, 8 figures, accepted for publication in JINS
A method for isolating and culturing placental cells from failed early equine pregnancies
Early pregnancy loss occurs in 6–10% of equine pregnancies making it the main cause of reproductive wastage. Despite this, reasons for the losses are known in only 16% of cases. Lack of viable conceptus material has inhibited investigations of many potential genetic and pathological causes. We present a method for isolating and culturing placental cells from failed early equine pregnancies. Trophoblast cells from 18/30 (60%) failed equine pregnancies of gestational ages 14–65 days were successfully cultured in three different media, with the greatest growth achieved for cells cultured in AmnioChrome™ Plus. Genomic DNA of a suitable quality for molecular assays was also isolated from 29/30 of these cases. This method will enable future investigations determining pathologies causing EPL
Electrons in a ferromagnetic metal with a domain wall
We present theoretical description of conduction electrons interacting with a
domain wall in ferromagnetic metals. The description takes into account
interaction between electrons. Within the semiclassical approximation we
calculate the spin and charge distributions, particularly their modification by
the domain wall. In the same approximation we calculate local transport
characteristics, including relaxation times and charge and spin conductivities.
It is shown that these parameters are significantly modified near the wall and
this modification depends on electron-electron interaction.Comment: 10 pages with 4 figure
Design and construction of new central and forward muon counters for CDF II
New scintillation counters have been designed and constructed for the CDF
upgrade in order to complete the muon coverage of the central CDF detector, and
to extend this coverage to larger pseudorapidity. A novel light collection
technique using wavelength shifting fibers, together with high quality
polystyrene-based scintillator resulted in compact counters with good and
stable light collection efficiency over lengths extending up to 320 cm. Their
design and construction is described and results of their initial performance
are reported.Comment: 20 pages, 15 figure
About the self-dual Chern-Simons system and Toda field theories on the noncommutative plane
The relation of the noncommutative self-dual Chern-Simons (NCSDCS) system to
the noncommutative generalizations of Toda and of affine Toda field theories is
investigated more deeply. This paper continues the programme initiated in , where it was presented how it is possible to define Toda
field theories through second order differential equation systems starting from
the NCSDCS system. Here we show that using the connection of the NCSDCS to the
noncommutative chiral model, exact solutions of the Toda field theories can be
also constructed by means of the noncommutative extension of the uniton method
proposed in by Ki-Myeong Lee. Particularly some
specific solutions of the nc Liouville model are explicit constructed.Comment: 24 page
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