New Evidence on Outlet Substitution Effects in Consumer Price Index Data

In this paper we provide new and detailed evidence on the impact on the U.S. CPI of the appearance and growth of new types of product outlets. Using actual CPI microdata for 2002-2007, we find that the changing mix of outlets had a statistically significantly negative impact on average prices in most of the 14 item food categories we study. In contrast to previous studies of this issue, our approach allows us to examine the effects of changes in outlet mix both across outlet types (such as among large groceries, discount department stores, and warehouse club stores) and within those outlet categories. We also adjust for numerous differences in item characteristics such as brand name, organic certification, and, importantly, package size. In our sample we find that the upward impact on price from increased item quality has offset most of the downward impact of lower-priced outlets. We also provide evidence showing that a simulated “matched-model” approach similar to that used in the CPI yields indexes that differ to a surprising extent from our baseline hedonic indexes, which also hold outlet and item mix constant.Outlet Bias, Consumer Price Index

Segmented X-Ray Optics for Future Space Telescopes

Lightweight and high resolution mirrors are needed for future space-based X-ray telescopes to achieve advances in high-energy astrophysics. The slumped glass mirror technology in development at NASA GSFC aims to build X-ray mirror modules with an area to mass ratio of approx.17 sq cm/kg at 1 keV and a resolution of 10 arc-sec Half Power Diameter (HPD) or better at an affordable cost. As the technology nears the performance requirements, additional engineering effort is needed to ensure the modules are compatible with space-flight. This paper describes Flight Mirror Assembly (FMA) designs for several X-ray astrophysics missions studied by NASA and defines generic driving requirements and subsequent verification tests necessary to advance technology readiness for mission implementation. The requirement to perform X-ray testing in a horizontal beam, based on the orientation of existing facilities, is particularly burdensome on the mirror technology, necessitating mechanical over-constraint of the mirror segments and stiffening of the modules in order to prevent self-weight deformation errors from dominating the measured performance. This requirement, in turn, drives the mass and complexity of the system while limiting the testable angular resolution. Design options for a vertical X-ray test facility alleviating these issues are explored. An alternate mirror and module design using kinematic constraint of the mirror segments, enabled by a vertical test facility, is proposed. The kinematic mounting concept has significant advantages including potential for higher angular resolution, simplified mirror integration, and relaxed thermal requirements. However, it presents new challenges including low vibration modes and imperfections in kinematic constraint. Implementation concepts overcoming these challenges are described along with preliminary test and analysis results demonstrating the feasibility of kinematically mounting slumped glass mirror segments

A Genome Sequence of Oceanimonas doudoroffii ATCC 27123T

Oceanimonas doudoroffii ATCC 27123T is an obligately aerobic Gram-negative rod of the class Gammaproteobacteria. It was first isolated from surface seawater off the coast of Oahu, HI, USA, in 1972. The predicted genome size is 3,832,938 bp (G+C content, 60.03%), which contains 3,524 predicted coding sequences