603 research outputs found
(1+1)-Dirac particle with position-dependent mass in complexified Lorentz scalar interactions: effectively PT-symmetric
The effect of the built-in supersymmetric quantum mechanical language on the
spectrum of the (1+1)-Dirac equation, with position-dependent mass (PDM) and
complexified Lorentz scalar interactions, is re-emphasized. The signature of
the "quasi-parity" on the Dirac particles' spectra is also studied. A Dirac
particle with PDM and complexified scalar interactions of the form S(z)=S(x-ib)
(an inversely linear plus linear, leading to a PT-symmetric oscillator model),
and S(x)=S_{r}(x)+iS_{i}(x) (a PT-symmetric Scarf II model) are considered.
Moreover, a first-order intertwining differential operator and an
-weak-pseudo-Hermiticity generator are presented and a complexified
PT-symmetric periodic-type model is used as an illustrative example.Comment: 11 pages, no figures, revise
First-order intertwining operators with position dependent mass and - weak-psuedo-Hermiticity generators
A Hermitian and an anti-Hermitian first-order intertwining operators are
introduced and a class of -weak-pseudo-Hermitian position-dependent mass
(PDM) Hamiltonians are constructed. A corresponding reference-target
-weak-pseudo-Hermitian PDM -- Hamiltonians' map is suggested. Some
-weak-pseudo-Hermitian PT -symmetric Scarf II and periodic-type models
are used as illustrative examples. Energy-levels crossing and flown-away states
phenomena are reported for the resulting Scarf II spectrum. Some of the
corresponding -weak-pseudo-Hermitian Scarf II- and
periodic-type-isospectral models (PT -symmetric and non-PT -symmetric) are
given as products of the reference-target map.Comment: 11 pages, no figures, Revised/Expanded, more references added. To
appear in the Int.J. Theor. Phy
Infection with Mansonella perstans Nematodes in Buruli Ulcer Patients, Ghana.
During August 2010-December 2012, we conducted a study of patients in Ghana who had Buruli ulcer, caused by Mycobacterium ulcerans, and found that 23% were co-infected with Mansonella perstans nematodes; 13% of controls also had M. perstans infection. M. perstans co-infection should be considered in the diagnosis and treatment of Buruli ulcer
Non linear pseudo-bosons versus hidden Hermiticity. II: The case of unbounded operators
Parallels between the notions of nonlinear pseudobosons and of an apparent
non-Hermiticity of observables as shown in paper I (arXiv: 1109.0605) are
demonstrated to survive the transition to the quantum models based on the use
of unbounded metric in the Hilbert space of states.Comment: 21 p
Hysteresis and Avalanches in the Random Anisotropy Ising Model
The behaviour of the Random Anisotropy Ising model at T=0 under local
relaxation dynamics is studied. The model includes a dominant ferromagnetic
interaction and assumes an infinite anisotropy at each site along local
anisotropy axes which are randomly aligned. Two different random distributions
of anisotropy axes have been studied. Both are characterized by a parameter
that allows control of the degree of disorder in the system. By using numerical
simulations we analyze the hysteresis loop properties and characterize the
statistical distribution of avalanches occuring during the metastable evolution
of the system driven by an external field. A disorder-induced critical point is
found in which the hysteresis loop changes from displaying a typical
ferromagnetic magnetization jump to a rather smooth loop exhibiting only tiny
avalanches. The critical point is characterized by a set of critical exponents,
which are consistent with the universal values proposed from the study of other
simpler models.Comment: 40 pages, 21 figures, Accepted for publication in Phys. Rev.
Copyright Contracts and Earnings of Visual Creators: A Survey of 5,800 British Designers, Fine Artists, Illustrators and Photographers
Neutrino masses from beta decays after KamLAND and WMAP (Updated including the NC enhanced SNO data)
The first data released by the KamLAND collaboration have confirmed the
strong evidence in favour of the LMA solution of the solar neutrino problem.
Taking into account the ranges for the oscillation parameters allowed by the
global analysis of the solar, CHOOZ and KamLAND data, we update the limits on
the neutrinoless double beta decay effective neutrino mass parameter and
analyze the impact of all the available data from neutrinoless double beta
decay experiments on the neutrino mass bounds, in view of the latest WMAP
results. For the normal neutrino mass spectrum the range (0.05-0.23) eV is
obtained for the lightest neutrino mass if one takes into account the
Heidelberg-Moscow evidence for neutrinoless double beta decay and the
cosmological bound. It is also shown that under the same conditions the mass of
the lightest neutrino may not be bounded from below if the spectrum is of the
inverted type. Finnaly, we discuss how future experiments can improve the
present bounds on the lightest neutrino mass set by the Troitsk, Mainz and WMAP
results. In the addendum we update the allowed ranges for the effective
Majorana neutrino mass parameter in view of the latest NC enhanced SNO data.Comment: Updated including the recent NC enhanced SNO data. Refferences added
and typos correcte
Non-Hermitian SUSY Hydrogen-like Hamiltonians with real spectra
It is shown that the radial part of the Hydrogen Hamiltonian factorizes as
the product of two not mutually adjoint first order differential operators plus
a complex constant epsilon. The 1-susy approach is used to construct
non-hermitian Hamiltonians with hydrogen spectra. Other non-hermitian
Hamiltonians are shown to admit an extra `complex energy' at epsilon. New
self-adjoint hydrogen-like Hamiltonians are also derived by using a 2-susy
transformation with complex conjugate pairs epsilon, (c.c) epsilon.Comment: LaTeX2e file, 13 pages, 6 EPS figures. New references added. The
present is a reorganized and simplified versio
Attentive Learning of Sequential Handwriting Movements: A Neural Network Model
Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)
Improving interinstitutional and intertechnology consistency of pulmonary SBRT by dose prescription to the mean internal target volume dose.
Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions.
This was a multi-institutional planning study by the German Society of Radiation Oncology (DEGRO) working group Radiosurgery and Stereotactic Radiotherapy. CT images and structures of ITV, PTV and all relevant organs at risk (OAR) for two patients with early stage non-small cell lung cancer (NSCLC) were distributed to all participating institutions. Each institute created a treatment plan with the technique commonly used in the institute for lung SBRT. The specified dose fractionation was 3 × 21.5 Gy normalized to the mean ITV dose. Additional dose objectives for target volumes and OAR were provided.
In all, 52 plans from 25 institutions were included in this analysis: 8 robotic radiosurgery (RRS), 34 intensity-modulated (MOD), and 10 3D-conformal (3D) radiation therapy plans. The distribution of the mean dose in the PTV did not differ significantly between the two patients (median 56.9 Gy vs 56.6 Gy). There was only a small difference between the techniques, with RRS having the lowest mean PTV dose with a median of 55.9 Gy followed by MOD plans with 56.7 Gy and 3D plans with 57.4 Gy having the highest. For the different organs at risk no significant difference between the techniques could be found.
This planning study pointed out that multiparameter dose prescription including normalization on the mean ITV dose in combination with detailed objectives for the PTV and ITV achieve consistent dose distributions for peripheral lung tumors in combination with an ITV concept between different delivery techniques and across institutions
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