When is an area law not an area law?

Entanglement entropy is typically proportional to area, but sometimes it acquires an additional logarithmic pre-factor. We offer some intuitive explanations for these facts.Comment: plainTeX, 12 pages, 3 figures. A more current version may be available at http://www.perimeterinstitute.ca/personal/rsorkin/some.papers

E-governance for efficient management to reduce corruption:An ICT driven paradigm

E-Governance to track and curtail unaccounted money is discussed. A new routine called Money card system using AAA for fund transfer is proposed. SaaS provided by cloud is used to compute the total possible income and expenditure. Service Oriented Architecture deployed in cloud architecture is proposed

NHDS: The New Hampshire Dispersion Relation Solver

NHDS is the New Hampshire Dispersion Relation Solver. This article describes the numerics of the solver and its capabilities. The code is available for download on https://github.com/danielver02/NHDS.Comment: 3 pages, 1 figur

A Parallel-Propagating Alfv\'enic Ion-Beam Instability in the High-Beta Solar Wind

We investigate the conditions under which parallel-propagating Alfv\'en/ion-cyclotron waves are driven unstable by an isotropic ($T_{\perp \alpha} = T_{\parallel\alpha}$) population of alpha particles drifting parallel to the magnetic field at an average speed $U_{\alpha}$ with respect to the protons. We derive an approximate analytic condition for the minimum value of $U_{\alpha}$ needed to excite this instability and refine this result using numerical solutions to the hot-plasma dispersion relation. When the alpha-particle number density is $\simeq 5$ of the proton number density and the two species have similar thermal speeds, the instability requires that $\beta_{\rm p} \gtrsim 1$, where $\beta_{\rm p}$ is the ratio of the proton pressure to the magnetic pressure. For $1\lesssim \beta_{\mathrm p}\lesssim 12$, the minimum $U_{\alpha}$ needed to excite this instability ranges from $0.7v_{\mathrm A}$ to $0.9v_{\mathrm A}$, where $v_{\mathrm A}$ is the Alfv\'en speed. This threshold is smaller than the threshold of $\simeq 1.2v_{\mathrm A}$ for the parallel magnetosonic instability, which was previously thought to have the lowest threshold of the alpha-particle beam instabilities at $\beta_{\mathrm p}\gtrsim 0.5$. We discuss the role of the parallel Alfv\'enic drift instability for the evolution of the alpha-particle drift speed in the solar wind. We also analyze measurements from the \emph{Wind} spacecraft's Faraday cups and show that the $U_{\alpha}$ values measured in solar-wind streams with $T_{\perp \alpha}\approx T_{\parallel\alpha}$ are approximately bounded from above by the threshold of the parallel Alfv\'enic instability.Comment: 8 pages, 7 figure