The “Honor” of LU’s Honors Program

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

The magnitude of the non-adiabatic pressure in the cosmic fluid

Understanding the non-adiabatic pressure, or relative entropy, perturbation is crucial for studies of early-universe vorticity and Cosmic Microwave Background observations. We calculate the evolution of the linear non-adiabatic pressure perturbation from radiation domination to late times, numerically solving the linear governing equations for a wide range of wavenumbers. Using adiabatic initial conditions consistent with WMAP seven year data, we find nevertheless that the non-adiabatic pressure perturbation is non-zero and grows at early times, peaking around the epoch of matter/radiation equality and decaying in matter domination. At early times or large redshifts (z=10,000) its power spectrum peaks at a comoving wavenumber k~0.2h/Mpc, while at late times (z=500) it peaks at k~0.02 h/Mpc.Comment: 5 pages, 4 figures. Replaced with version accepted by MNRAS. One figure removed, added some discussio

Losing Ground: Income and Poverty in Upstate New York, 1980-2000

Over the past several decades, Upstate New York has transitioned from a stable middle-income region to one with serious income and economic problems. In 1969, per capita personal income (PCPI) in Upstate exceeded that of the United States, but by 2000, it trailed the national average by 11 percent. These lagging incomes likely contribute to the substantial out-migration of mobile residents from the area—especially in the mid-1990s—which in turn is threatening economic growth. At the same time, many of those who stay increasingly lack the resources to pay for goods and services that other U.S. residents enjoy, further exacerbating economic stagnation in the region. Both of these trends—population decline and economic malaise—are the subjects of other recent reports in this series

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