Non-Hermitian matrix description of the PT symmetric anharmonic oscillators

Schroedinger equation H \psi=E \psi with PT - symmetric differential operator H=H(x) = p^2 + a x^4 + i \beta x^3 +c x^2+i \delta x = H^*(-x) on L_2(-\infty,\infty) is re-arranged as a linear algebraic diagonalization at a>0. The proof of this non-variational construction is given. Our Taylor series form of \psi complements and completes the recent terminating solutions as obtained for certain couplings \delta at the less common negative a.Comment: 18 pages, latex, no figures, thoroughly revised (incl. title), J. Phys. A: Math. Gen., to appea

Study of a class of non-polynomial oscillator potentials

We develop a variational method to obtain accurate bounds for the eigenenergies of H = -Delta + V in arbitrary dimensions N>1, where V(r) is the nonpolynomial oscillator potential V(r) = r^2 + lambda r^2/(1+gr^2), lambda in (-infinity,\infinity), g>0. The variational bounds are compared with results previously obtained in the literature. An infinite set of exact solutions is also obtained and used as a source of comparison eigenvalues.Comment: 16 page

PT symmetric models in more dimensions and solvable square-well versions of their angular Schroedinger equations

For any central potential V in D dimensions, the angular Schroedinger equation remains the same and defines the so called hyperspherical harmonics. For non-central models, the situation is more complicated. We contemplate two examples in the plane: (1) the partial differential Calogero's three-body model (without centre of mass and with an impenetrable core in the two-body interaction), and (2) the Smorodinsky-Winternitz' superintegrable harmonic oscillator (with one or two impenetrable barriers). These examples are solvable due to the presence of the barriers. We contemplate a small complex shift of the angle. This creates a problem: the barriers become "translucent" and the angular potentials cease to be solvable, having the sextuple-well form for Calogero model and the quadruple or double well form otherwise. We mimic the effect of these potentials on the spectrum by the multiple, purely imaginary square wells and tabulate and discuss the result in the first nontrivial double-well case.Comment: 21 pages, 5 figures (see version 1), amendment (a single comment added on p. 7

Gated myocardial perfusion SPECT underestimates left ventricular volumes and shows high variability compared to cardiac magnetic resonance imaging -- a comparison of four different commercial automated software packages

Abstract Background We sought to compare quantification of left ventricular volumes and ejection fraction by different gated myocardial perfusion SPECT (MPS) programs with each other and to magnetic resonance (MR) imaging. Methods N = 100 patients with known or suspected coronary artery disease were examined at rest with 99 mTc-tetrofosmin gated MPS and cardiac MR imaging. Left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were obtained by analysing gated MPS data with four different programs: Quantitative Gated SPECT (QGS), GE MyoMetrix, Emory Cardiac Toolbox (ECTb) and Exini heart. Results All programs showed a mean bias compared to MR imaging of approximately -30% for EDV (-22 to -34%, p Conclusions Gated MPS, systematically underestimates left ventricular volumes by approximately 30% and shows a high variability, especially for ESV. For EF, accuracy was better, with a mean bias between -15 and 6% of EF. It may be of value to take this into consideration when determining absolute values of LV volumes and EF in a clinical setting.</p

Effects of lazaroids on intestinal ischemia and reperfusion injury in experimental models

Mesenteric ischemia occurs in a number of clinically relevant pathophysiologic processes, including sepsis, hemorrhage, intestinal transplantation, severe burns, and mesenteric thrombosis. The readmission of molecular oxygen into an ischemic tissue promotes the oxidation of resuscitated tissue with certain pathophysiologic mechanisms. Depending on the duration and the intensity of ischemia, reoxygenation of the intestine that has been reperfused may further induce tissue injury. Intestinal ischemia and reperfusion injury can accelerate complex processes between the endothelium and different cell types leading to microvascular injury, cellular necrosis, and apoptosis. The injury due to reperfusion is found predominantly in the intestinal mucosa and submucosa, causing endothelial detachment. The 21-aminosteroids (lazaroids) are a family of compounds that inhibit lipid membrane peroxidation. Many of the performed studies show conflicting results, which reflect differences in experimental design, evolving time that (I/R) is induced, total or partial vascular occlusion, dosage of the lazaroid, and the exact period of time that the lazaroid is administered. © 2011 Elsevier Inc. All rights reserved

SNAIL FARMING IN NET-COVERED GREENHOUSES: A COMPARISON BETWEEN SEMI-NATURAL AND ARTIFICIAL CONDITIONS

The suitable climatic conditions for rearing snails (Cornu aspersum and Helix lucorum) were investigated in a net greenhouse (Volos Greece). Temperature and Relative Humidity were evaluated during light and darkness for the period of a month. In addition, snails’ growth was recorded. In October 2011, with the fog system in operation, the temperature inside the net – house was recorded to be lower than outside (14,38°C - 16,9°C). The Relative Humidity was in a very good level regarding the interior (85,13%). The next year (October 2012) in semi natural conditions, air temperature was higher inside (21,43°C), although the relative humidity was significantly lower (53,3%)