Time-dependent non-Hermitian Hamiltonians with real energies

In this work we intend to study a class of time-dependent quantum systems with non-Hermitian Hamiltonians, particularly those whose Hermitian counterparts are important for the comprehension of posed problems in quantum optics and quantum chemistry. They consist of an oscillator with time-dependent mass and frequency under the action of a time-dependent imaginary potential. The wave functions are used to obtain the expectation value of the Hamiltonian. Although it is neither Hermitian nor PT symmetric, the Hamiltonian under study exhibits real values of energy.

ANOMALOUS CONTRIBUTIONS TO E+E- -] E+E-L+L- AT HIGH-ENERGIES

We analyze the process e+ e- --> e+ e- gamma-gamma --> e+ e- l+ l- (l = e, mu, tau-leptons) considering several nonstandard contributions in order to search for new physics beyond the standard model. We are able to test compositeness up to the TeV mass scale at LEP II and CLIC energies.

Supersymmetric variational energies of 3d confined potentials

Within the approach of supersymmetric quantum mechanics associated with the variational method a recipe to construct the superpotential of three-dimensional confined potentials in general is proposed. To illustrate the construction, the energies of the harmonic oscillator and the Hulthen potential, both confined in three dimensions are evaluated. Comparison with the corresponding results of other approximative and exact numerical results is presented. (C) 2003 Elsevier B.V. All rights reserved.

Investigation of the electrical properties of SnO2 varistor system using impedance spectroscopy

The electrical properties of tin oxide varistors doped with CoO, Nb2O5 and Cr2O3, were investigated using the impedance spectroscopy technique with the temperature ranging from 25 to 400 degrees C. The impedance data, represented by means of Nyquist diagrams, show two time constants with different activation energies, one at low frequencies and the other at high frequencies. These activation energies were associated with the adsorption and reaction of O-2 species at the grain boundary interface. The Arrhenius plots show two slopes with a turnover at 200 degrees C for both the higher and lower frequency time constants. This behavior can be related with the decrease of minor charge carrier density. The barrier formation mechanism was associated with the presence of Cr-Sn at the surface, which promotes the adsorption of the O' and O species which are in turn proposed as being responsible for the barrier formation. (C) 1998 American Institute of Physics. [S0021-8979(98)04719-7]

Surgical treatment of erythroleukoplakia in lower lip with carbon dioxide laser radiation

Erythroplakia is considered to represent a premalignant condition and is felt to be at high risk to progress to oral cancer development. When the lesion presents with red and white mucosal alterations concomitantly, the term erythroleukoplakia is used. However, in erythroleukoplakia lesions, the red or erythroplakia areas have been shown to be most likely to demonstrate dysplastic changes compared to the white hyperkeratotic areas. We present a case of patient with erythroleukoplakia involving the lower lip that was treating with carbon dioxide laser radiation (CO2) with 0.8 mm focus, 5 W, power density of 2.5 W/cm(2) in continuous. After the surgery, the vaporized surface was protected with a fibrinolisine + chloramphenicol cream. To date, after 6 months, there has been no clinically evident recurrence on the vermilion area. The functional and esthetic results observed were judged to be excellent.

Relationship between lower-lip fistulae and cleft lip and/or palate in Van der Woude syndrome

Objective: This study was conducted to evaluate the relationship between fistulae of the lower lip and cleft lip and/or palate in patients with Van der Woude syndrome.Methods: the medical records of 11,000 patients with cleft lip and/or palate registered at the Cleft Lip-Palate Research and Rehabilitation Hospital, University of São Paulo, Bauru were reviewed. of these patients, 133 (1.2%) presented with Van der Woude syndrome.Results: of the 133 patients, 88 (66.2%) exhibited full clefts, 22 (16.5%) only cleft lip, and 23 (17.3%) only cleft palate. The lower-lip fistulae observed in these 133 patients were bilateral symmetric in 66 (49.7%), bilateral asymmetric in 42 (31.6%), microform in 19 (14.3%), median in 5 (3.8%), and unilateral in 1 (0.7%).Conclusion: This population sample appears to exhibit the previously published tendency for bilateral, unilateral, or mixed-type congenital fistulae to be associated with cleft lip with or without cleft palate, while so-called microforms or conic elevations are almost exclusively associated with cleft palate.

Supersymmetric variational energies for the confined Coulomb system

The methodology based on the association of the variational method with supersymmetric quantum mechanics is used to evaluate the energy states of the confined hydrogen atom. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Photoinduced birefringence at low temperatures in Langmuir-Blodgett films of azobenzene-functionalized copolymers

The temperature dependence has been investigated for the photoinduced birefringence in Langmuir-Blodgett (LB) films from the azocopolymer 4-[N- ethyl -N-(2-hydroxyethyl)] amino-2'-chloro-4'-nitroazobenzene (MMA-DR13) mixed with cadmium stearate. The buildup and relaxation of the birefringence in the range from 20 to 296 K were fitted with a Kohlrausch-Williams-Watts (KWW) function, with a beta-value of 0.78-0.98 for the build-up and 0.18-0.27 for the decay. This is consistent with a distribution of time constants for the kinetics of the birefringence processes. The maximum birefringence increased with increasing temperature up to 120 K because the free volume fluctuation also increased with temperature. Above 120 K, the birefringence decreased with temperature as thermal diffusion dominates. In the latter range of temperature, an Arrhenius behavior is inferred for both build-up and decay of birefringence. In each case two activation energies were obtained: 0.8 and 5 kJ/mol for the build-up and 10 and 30 kJ/mol for the decay. The energies for the build-up are much lower than those associated with motion of the polymer chain, which means that the dynamics is governed by the orientation of the chromophores. For the decay, local motion of lateral groups of the polymer chains becomes important as the activation energies are within the range of gamma-relaxation energies. (C) 2003 Elsevier B.V. B.V. All rights reserved.

The non-adiabatic hyperspherical approach to the two-dimensional D- ion in the presence of a magnetic field

We have used the adiabatic hyperspherical approach to determine the energies and wave functions of the ground state and first excited states of a two-dimensional D- ion in the presence of a magnetic field. Using a modified hyperspherical angular variable, potential energy curves are analytically obtained, allowing an accurate determination of the energy levels of this system. Upper and lower bounds for the ground-state energy have been determined by a non-adiabatic procedure, as the purpose is to improve the accuracy of method. The results are shown to be comparable to the best variational calculations reported in the literature.

When the Casimir energy is not a sum of zero-point energies

We compute the leading radiative correction to the Casimir force between two parallel plates in the lambdaPhi(4) theory. Dirichlet and periodic boundary conditions are considered. A heuristic approach, in which the Casimir energy is computed as the sum of one-loop corrected zero-point energies, is shown to yield incorrect results, but we show how to amend it. The technique is then used in the case of periodic boundary conditions to construct a perturbative expansion which is free of infrared singularities in the massless limit. In this case we also compute the next-to-leading order radiative correction, which turns out to be proportional to lambda(3/2).