An exact solution to the Dirac equation for a time dependent Hamiltonian in 1-1D space-time

We find an exact solution to the Dirac equation in 1-1 dimensional space-time in the presence of a time-dependent potential which consists of a combination of electric, scalar, and pseudoscalar terms.Comment: Five page

On the Dirac equation with PT-symmetric potentials in the presence of position-dependent mass

The relativistic problem of fermions subject to a PT-symmetric potential in the presence of position-dependent mass is reinvestigated. The influence of the PT-symmetric potential in the continuity equation and in the orthonormalization condition are analyzed. In addition, a misconception diffused in the literature on the interaction of neutral fermions is clarified.Comment: 8 page

A new species of Prosekia (Philosciidae, Isopoda) from an inundation forest (igapó) in the Central Amazon

Prosekia tarumae n. sp. (Philosciidae, Isopoda) from a Central Amazonian black-water inundation forest (lgapó) is described

Comment on "Wave functions for a Duffin-Kemmer-Petiau particle in a time-dependent potential"

It is shown that the paper "Wave functions for a Duffin-Kemmer-Petiau particle in a time-dependent potential", by Merad and Bensaid [J. Math. Phys. 48, 073515 (2007)] is not correct in using inadvertently a non-Hermitian Hamiltonian in a formalism that does require Hermitian Hamiltonians.Comment: 2 page

Quantitative Isoperimetric Inequalities on the Real Line

In a recent paper A. Cianchi, N. Fusco, F. Maggi, and A. Pratelli have shown that, in the Gauss space, a set of given measure and almost minimal Gauss boundary measure is necessarily close to be a half-space. Using only geometric tools, we extend their result to all symmetric log-concave measures \mu on the real line. We give sharp quantitative isoperimetric inequalities and prove that among sets of given measure and given asymmetry (distance to half line, i.e. distance to sets of minimal perimeter), the intervals or complements of intervals have minimal perimeter.Comment: 14 pages, 3 figure

Unsuitable use of spin and pseudospin symmetries with a pseudoscalar Cornell potential

The concepts of spin and pseudospin symmetries has been used as mere rhetorics to decorate the pseudoscalar potential [Chin. Phys. B 22 090301 (2013)]. It is also pointed out that a more complete analysis of the bound states of fermions in a a pseudoscalar Cornell potential has already been published elsewhere.Comment: 6 pages, to appear in Chi. Phys.

Trapping neutral fermions with kink-like potentials

The intrinsically relativistic problem of neutral fermions subject to kink--like potentials ($\sim \mathrm{tanh} \gamma x$) is investigated and the exact bound-state solutions are found. Apart from the lonely hump solutions for $E=\pm mc^{2}$, the problem is mapped into the exactly solvable Surm-Liouville problem with a modified P\"{o}schl-Teller potential. An apparent paradox concerning the uncertainty principle is solved by resorting to the concepts of effective mass and effective Compton wavelength.Comment: 13 page

On the bound-state spectrum of a nonrelativistic particle in the background of a short-ranged linear potential

The nonrelativistic problem of a particle immersed in a triangular potential well, set forth by N.A. Rao and B.A. Kagali, is revised. It is shown that these researchers misunderstood the full meaning of the potential and obtained a wrong quantization condition. By exploring the space inversion symmetry, this work presents the correct solution to this problem with potential applications in electronics in a simple and transparent way