Particle creation and particle number in an expanding universe

I describe the logical basis of the method that I developed in 1962 and 1963 to define a quantum operator corresponding to the observable particle number of a quantized free scalar field in a spatially-flat isotropically expanding (and/or contracting) universe. This work also showed for the first time that particles were created from the vacuum by the curved space-time of an expanding spatially-flat FLRW universe. The same process is responsible for creating the nearly scale-invariant spectrum of quantized perturbations of the inflaton scalar field during the inflationary stage of the expansion of the universe. I explain how the method that I used to obtain the observable particle number operator involved adiabatic invariance of the particle number (hence, the name adiabatic regularization) and the quantum theory of measurement of particle number in an expanding universe. I also show how I was led in a surprising way, to the discovery in 1964 that there would be no particle creation by these spatially-flat FLRW universes for free fields of any integer or half-integer spin satisfying field equations that are invariant under conformal transformations of the metric. The methods I used to define adiabatic regularization for particle number, were based on generally-covariant concepts like adiabatic invariance and measurement that were fundamental and determined results that were unique to each given adiabatic order.Comment: 22 pages, no figures, submitted 7May2012 to J. Phys. A for a special issue honoring Prof. Stuart Dowke

Nonlocal theory of area-varying waves on axisymmetric vortex tubes

Area and axial flow variations on rectilinear vortex tubes are considered. The state of the flow is characterized by two dependent variables, a core area, and an azimuthal circulation per unit length, which vary in time and in distance along the length of the tube. Nonlinear integrodifferential equations of motion for these variables are derived by taking certain integrals of the vorticity transport equation. The equations are argued to be valid for moderately short waves (on the order of a few core radii) as well as for long waves. Applications to vortex breakdown and other wave phenomena are considered

Assessing year to year variability of inertial oscillation in the Chukchi Sea using the wavelet transform

Master's Project (M.S.) University of Alaska Fairbanks, 2016Three years of ocean drifter data from the Chukchi Sea were examined using the wavelet transform to investigate inertial oscillation. There was an increasing trend in number, duration, and hence total proportion of time spent in inertial oscillation events. Additionally, the Chukchi Sea seems to facilitate inertial oscillation that is easier to discern using north-south velocity records rather than east-west velocity records. The data used in this analysis was transformed using wavelets, which are generally used as a qualitative statistical method. Because of this, in addition to measurement error and random ocean noise, there is an additional source of variability and correlation which makes concrete statistical results challenging to obtain. However, wavelets were an effective tool for isolating the specific period of inertial oscillation and examining how it changed over time

Global school relationships. School linking and future challenges

The process of School Linking has attained a raised profile in UK Development Education circles in recent years. This paper reviews recent literature ans issues. It set out to answer these research questions: What is the interest in North-South School Links for people in the North and the South and what are possible contradictions? How in the School Linking process currently evaluated? Arising from these research questions, the concluding section seeks to identify the challenges for further Links and potential research topics in the field. (DIPF/Orig.)Schulpartnerschaftsarbeit zwischen Nord und Süd hat in den letzten Jahren im Kontext des Globalen Lernens in Großbritannien an Profil gewonnen. In diesem Beitrag wird ein Überblick über die aktuelle Diskussion gegeben. Zudem werden Forschungsfragen thematisiert: Was sind Interessen und Ziele in der Schulpartnerschaftsarbeit und was sind mögliche Widersprüche dieser Arbeit? Wie wird diese Arbeit evaluiert? Anschließend werden die zukünftigen Herausforderungen dieser Arbeit benannt. (DIPF/Orig.