Wave dispersion derived from the square-root Klein-Gordon-Poisson system

Recently there has been great interest around quantum relativistic models for plasmas. In particular striking advances have been obtained by means of the Klein-Gordon-Maxwell system, which provides a first order approach to the relativistic regimes of quantum plasmas. It is a reliable method as long as the plasma spin dynamics is not a fundamental aspect, to be addressed using more refined (and heavier) models involving the Pauli-Schr\"odinger or Dirac equations. In this work a further simplification is considered, tracing back to the early days of relativistic quantum theory. Namely, we revisit the square-root Klein-Gordon-Poisson system, where the positive branch of the relativistic energy-momentum relation is mapped to a quantum wave equation. The associated linear wave propagation is analyzed and compared to the results in the literature. We determine physical parameters where the simultaneous quantum and relativistic effects can be noticeable in weakly coupled electrostatic plasmas

Sovereign debt: Do we need an EU solution? Bertelsmann Stiftung EUROPA Briefing 2017

High levels of sovereign debt have become a serious issue in the Eurozone. This does not just affect the individual member states: The European debt crisis has shown that difficulties in one euro-area country can spread to the entire currency union. What strategies are being discussed for reducing sovereign debt? Would a stronger role for the EU help to reduce debt over the long term or should this be left solely to the member states

Can hierarchical predictive coding explain binocular rivalry?

Hohwy et al.’s (2008) model of binocular rivalry (BR) is taken as a classic illustration of predictive coding’s explanatory power. I revisit the account and show that it cannot explain the role of reward in BR. I then consider a more recent version of Bayesian model averaging, which recasts the role of reward in (BR) in terms of optimism bias. If we accept this account, however, then we must reconsider our conception of perception. On this latter view, I argue, organisms engage in what amounts to policy-driven, motivated perception

Airborne electromagnetic sea ice thickness sounding in shallow, brackish water environments of the Caspian and Baltic Seas

Ice engineering projects often rely on the knowledge of ice thickness in shallow, brackish water like in the Baltic and Caspian Seas. By means of field data and model results, the paper shows that helicopter-borne electromagnetic induction measurements using frequencies of 3.68 and 112 kHz can yield accurate thickness estimates with salinities as low as 3 ppt. The higher frequency yields the strongest EM signals. In addition, in shallow water the higher frequency is less sensitive to the sea floor signal, and can thus be used in water depths as shallow as 4-6 m, depending on flying altitude. Because the low frequency signal is very sensitive on shallow water depth, a combination of both signals will allow the retrieval of both ice thickness and water depth

Harris sheet solution for magnetized quantum plasmas

We construct an infinite family of one-dimensional equilibrium solutions for purely magnetized quantum plasmas described by the quantum hydrodynamic model. The equilibria depends on the solution of a third-order ordinary differential equation, which is written in terms of two free functions. One of these free functions is associated to the magnetic field configuration, while the other is specified by an equation of state. The case of a Harris sheet type magnetic field, together with an isothermal distribution, is treated in detail. In contrast to the classical Harris sheet solution, the quantum case exhibits an oscillatory pattern for the density.Comment: 2 figure