The “Honor” of LU’s Honors Program

Kristen Christoperson recounts her experience of being an Honors student at Liberty Universit

Calculating Non-adiabatic Pressure Perturbations during Multi-field Inflation

Isocurvature perturbations naturally occur in models of inflation consisting of more than one scalar field. In this paper we calculate the spectrum of isocurvature perturbations generated at the end of inflation for three different inflationary models consisting of two canonical scalar fields. The amount of non-adiabatic pressure present at the end of inflation can have observational consequences through the generation of vorticity and subsequently the sourcing of B-mode polarisation. We compare two different definitions of isocurvature perturbations and show how these quantities evolve in different ways during inflation. Our results are calculated using the open source Pyflation numerical package which is available to download.Comment: v2: Typos fixed, references and comments added; v1: 8 pages, 10 figures, software available to download at http://pyflation.ianhuston.ne

The Elements of a Perfected Song Cycle: A Lecture Recital on Schumann’s Frauenliebe und Leben

A lecture recital is a quintessential representation of the music student’s knowledge and skill in a synthesis of performance and instruction. This thesis will encompass the extensive research and preparation necessary to perform a lecture recital about Robert Schumann’s song cycle Frauenliebe und Leben (A Woman’s Love and Life). This marvelous work is an excellent example of Schumann’s enhancement of the song cycle genre. A standard work in soprano repertoire, Frauenliebe und Leben provides the opportunity for extensive musicality through vocal coloring, legato lines, ornamented turns, various phrasal structures, and clear dramatic direction. In addition to its rich history and theory, precise vocal technique and musical interpretation are necessary to present a successful performance of this piece

Estimating the amount of vorticity generated by cosmological perturbations in the early universe

We estimate the amount of vorticity generated at second order in cosmological perturbation theory from the coupling between first order energy density and non-adiabatic pressure, or entropy, perturbations. Assuming power law input spectra for the source terms, and working in a radiation background, we calculate the wave number dependence of the vorticity power spectrum and its amplitude. We show that the vorticity generated by this mechanism is non-negligible on small scales, and hence should be taken into consideration in current and future CMB experiments.Comment: 9 pages, revtex4, 1 figure; v2: typos and minor error corrected, result unchange

A simplified structure for the second order cosmological perturbation equations

Increasingly accurate observations of the cosmic microwave background and the large scale distribution of galaxies necessitate the study of nonlinear perturbations of Friedmann-Lemaitre cosmologies, whose equations are notoriously complicated. In this paper we present a new derivation of the governing equations for second order perturbations within the framework of the metric-based approach that is minimal, as regards amount of calculation and length of expressions, and flexible, as regards choice of gauge and stress-energy tensor. Because of their generality and the simplicity of their structure our equations provide a convenient starting point for determining the behaviour of nonlinear perturbations of FL cosmologies with any given stress-energy content, using either the Poisson gauge or the uniform curvature gauge.Comment: 30 pages, no figures. Changed title to the one in published version and some minor changes and addition

Long Term Vacancy and Residential Abandonment in Minneapolis.

Supported by the Center for Urban and Regional Affairs, University of Minnesota

Modelling non-dust fluids in cosmology

Currently, most of the numerical simulations of structure formation use Newtonian gravity. When modelling pressureless dark matter, or `dust', this approach gives the correct results for scales much smaller than the cosmological horizon, but for scenarios in which the fluid has pressure this is no longer the case. In this article, we present the correspondence of perturbations in Newtonian and cosmological perturbation theory, showing exact mathematical equivalence for pressureless matter, and giving the relativistic corrections for matter with pressure. As an example, we study the case of scalar field dark matter which features non-zero pressure perturbations. We discuss some problems which may arise when evolving the perturbations in this model with Newtonian numerical simulations and with CMB Boltzmann codes.Comment: 5 pages; v2: typos corrected and refs added, submitted version; v3: version to appear in JCA

Prostitution, Condom Use, and Invasive Squamous Cell Cervical Cancer in Thailand

Cervical cancer is probably caused by a sexually transmitted agent. A case-control study was conducted in three hospitals in Thailand to investigate further the role of male sexual behavior, particularly regarding sexual contacts with prostitutes, in the development of this disease. Data were obtained from interviews with 225 married women with invasive squamous cell cervical carcinoma and 791 hospitalized controls, all of whom reported having only one sexual partner, and from interviews with their husbands. Risk of cervical cancer was strongly related to the women's husbands having visited prostitutes without using a condom when the husbands were less than 30 years old. A strong increasing trend in risk in relation to decreasing frequency of the husbands' condom use with prostitutes was observed, and a weaker increasing trend in risk with husbands' estimated lifetime total number of visits to prostitutes was found. The average latent period between the women's likely initial exposure to a sexually transmitted oncogenic agent and her diagnosis of invasive cervical cancer was about a quarter of a century. Regular use of condoms by customers of prostitutes could reduce the number of invasive cervical cancer cases in the general population of Thailand by at least one fourth. Am J Epidemiol 1996; 143: 779-8

Evaluation of SSC Cable Produced for the Model Dipole Program during 1989 and through February, 1990

During 1989 and the beginning of 1990, approximately 150,000 feet of cable was manufactured for use in the SSC Model Dipole Magnet Program. The wire for the cable was made to SSC specifications by three different manufacturers. The cable was made at New England Electric Wire on the SSC Production Cabling Machine, under supervision of either SSC Laboratory personnel or the wire manufacturer's representative. All the cable produced for SSC model dipoles was subjected to rigorous inspection in order to insure that ths magnet construction and performance would be predictable. The cable dimensions were measured at intervals of 10 feet or less with a cable measuring machine. Electrical properties were measured on samples from one end of each cable length. Critical current degradation due to cabling was checked by measuring the critical currents of the wires used to make the cable and comparing these with the cable critical current. The results of the dimensional and electrical measurements will be discussed and compared with the SSC specification requirements