Zimbabwe’s Hyperinflation Money Demand Model

The research attempts to empirically study the demand for money, especially the magnitudes of the price expectation and real cash balance adjustment for Zimbabwe. Price expectation and real cash balance adjustment models are estimated. The results show that both the interest rate and the rate of change in prices are relevant variables for explaining the variations in the demand for real cash balances in Zimbabwe. Overall, the findings suggest that the Zimbabwean hyperinflation does not appear to have been a self- generating process independent of money supply.Hyperinflation, Real Cash Balances, Price Expectation, Equilibrium, Error Correction Model

On the robustness of q-expectation values and Renyi entropy

We study the robustness of functionals of probability distributions such as the R\'enyi and nonadditive S_q entropies, as well as the q-expectation values under small variations of the distributions. We focus on three important types of distribution functions, namely (i) continuous bounded (ii) discrete with finite number of states, and (iii) discrete with infinite number of states. The physical concept of robustness is contrasted with the mathematically stronger condition of stability and Lesche-stability for functionals. We explicitly demonstrate that, in the case of continuous distributions, once unbounded distributions and those leading to negative entropy are excluded, both Renyi and nonadditive S_q entropies as well as the q-expectation values are robust. For the discrete finite case, the Renyi and nonadditive S_q entropies and the q-expectation values are robust. For the infinite discrete case, where both Renyi entropy and q-expectations are known to violate Lesche-stability and stability respectively, we show that one can nevertheless state conditions which guarantee physical robustness.Comment: 6 pages, to appear in Euro Phys Let

Quantum anholonomies in time-dependent Aharonov-Bohm rings

Anholonomies in eigenstates are studied through time-dependent variations of a magnetic flux in an Aharonov-Bohm ring. The anholonomies in the eigenenergy and the expectation values of eigenstates are shown to persist beyond the adiabatic regime. The choice of the gauge of the magnetic flux is shown to be crucial to clarify the relationship of these anholonomies to the eigenspace anholonomy, which is described by a non-Abelian connection in the adiabatic limit.Comment: 6 pages. Fixed typ

Geometry induced entanglement transitions in nanostructures

We model quantum dot nanostructures using a one-dimensional system of two interacting electrons. We show that strong and rapid variations may be induced in the spatial entanglement by varying the nanostructure geometry. We investigate the position-space information entropy as an indicator of the entanglement in this system. We also consider the expectation value of the Coulomb interaction and the ratio of this expectation to the expectation of the confining potential and their link to the entanglement. We look at the first derivative of the entanglement and the position-space information entropy to infer information about a possible quantum phase transition.Comment: 3 pages, 2 figures, to appear in Journal of Applied Physic

Understanding the spectral hardenings and radial distribution of Galactic cosmic rays and Fermi diffuse gamma-rays with spatially-dependent propagation

Recent direct measurements of Galactic cosmic ray spectra by balloon/space-borne detectors reveal spectral hardenings of all major nucleus species at rigidities of a few hundred GV. The all-sky diffuse gamma-ray emissions measured by the Fermi Large Area Telescope also show spatial variations of the intensities and spectral indices of cosmic rays. These new observations challenge the traditional simple acceleration and/or propagation scenario of Galactic cosmic rays. In this work we propose a spatially-dependent diffusion scenario to explain all these phenomena. The diffusion coefficient is assumed to be anti-correlated with the source distribution, which is a natural expectation from the charged particle transportation in turbulent magnetic field. The spatially-dependent diffusion model also gives a lower level of anisotropies of cosmic rays, which are consistent with observations by underground muons and air shower experiments. The spectral variations of cosmic rays across the Galaxy can be properly reproduced by this model.Comment: accepted by PR

Superpositions of up to six plane waves without electric-field interference

Superpositions of coherent light waves typically interfere. We present superpositions of up to six plane waves that defy this expectation by having a perfectly homogeneous mean square of the electric field. For many applications in optics, these superpositions can be seen as having a homogeneous intensity. Our superpositions show interesting one-, two-, and three-dimensional patterns in their helicity densities, including several that support bright regions of superchirality. Our superpositions might be used to write chiral patterns in certain materials, and, conversely, such materials might be used as the basis of an “optical helicity camera” capable of recording spatial variations in helicity