Regional and temporal dimensions of metropolitan area wage structures

Principal components analysis is applied to occupational wage data for a sample of metropolitan areas. Indexes of wage levels and skilled/unskilled differentials are derived. Areas in the same region tend to have similar wage structures, which have changed little over twenty years. A simple regression model is reasonably successful in explaining interarea variation in the two dimensions.The views expressed are the author's and do not represent any official position of the Bureau of Labor Statistics.     

Zinc Iron Chromite Pigments

The system ZnO–Fe₂O₃–Cr₂O₃ is the basis of most of the brown pigments used in the whitewares industry. The ability of iron to occur on both the tetrahedral and octahedral sites of the spinel structure leads to a versatile system yielding a variety of related shades.     

Empty dwellings and tenure switching: A British case study

It has been long recognised that vacant dwellings represent a serious waste of at least a part of the housing stock. Yet our knowledge of this issue, and the nature of the economic, social, political and legal processes which both explain and determine the level of vacancy, remains limited. In this paper an explanatory framework for the analysis of vacancies is presented, together with the empirical results from research in one inner London borough. The findings show that in addition to facilitating household mobility and stock rehabilitation, the processes which create vacancies determine their duration, and govern eventual access to them, are, in the private sector, closely allied with tenure change.     

Mechanisms of fracture in filled thermosetting resins

Fracture properties of a wide range of filled unsaturated polyester resin composites have been investigated with respect to filler size, shape, loading and adhesion to the matrix resin. Mechanisms are proposed for the fracture behaviors found, based on geometrical considerations of interacting filler particles and stress concentrations which result from them.     

The impact of collinearity involving the intercept term on the numerical accuracy of regression

It is well known that multiple linear regression models with ill-conditioning can produce coefficient estimates with degraded numerical accuracy. This study examines the numerical accuracy of regression algorithms in the presence a particular type of ill-conditioning, that arising from collinear relationships that involve the intercept term and the independent variables. A benchmark data set is used to produce ill-conditioned data by introducing near linear relationships among the independent variables and the intercept term. The experiments reported here demonstrate that centering does not prevent a loss in numerical accuracy for this particular type of ill-conditioning. In addition, the ability of commonly used diagnostic checks to detect these problems is studied. As an example of the problems that arise from ignoring the relationships studied here we demonstrate that the regression procedures in two widely used statistical packages, SAS and SPSS-X, fail to detect this type of ill-conditioning and report highly inaccurate coefficient estimates.     

Influence of stress on morphine-induced hyperthermia: Relevance to drug conditioning and tolerance development.

Three experiments, with 64 Holtzman and 48 Wistar male rats, examined whether Ss would become tolerant, or sensitized, to morphine-induced hyperthermia and the directionality of the conditioned pyretic effects of morphine. Stress produced by temperature-assessment procedures affected Ss' pyretic response to morphine. Under conditions of high stress, Ss first showed diminished, and then enhanced, hyperthermic responding across repeated dosing with morphine sulfate (5 or 35 mg/kg, sc). The diminished hyperthermia can be attributed to habituation to high levels of assessment stress. Repeated morphine doses delivered under conditions of low stress produced only enhanced hyperthermic responding, indicating that Ss became sensitized to morphine's hyperthermic effects. There was little evidence that morphine supported conditioning of pyretic responses. The temperature-assessment stress that produced hyperthermia was mediated by opiate peptides, was blocked by naloxone, and enhanced the agonist effects of morphine. Implications for theories of drug conditioning and tolerance are discussed. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strategic allocation of inspection stations for a flow assembly line: a hybrid procedure

A hybrid method is presented for the design of inspection stations in serial production systems. The hybrid method combines a constrained bottleneck shortest path algorithm and discrete event simulation. The network method determines the allocation of the inspection stations and the simulation helps the decision maker estimate accurately the possible outcome of the allocation. A computational study with the method is performed based on a practical problem. Other aspects related to the application of the method to real problems are also discussed.     

Frequency domain stress intensity calibration of damped cracked panels

This paper discusses two schemes for doing finite element K calibration in the frequency domain. The baseline scheme uses the definition of K as a limit toward the crack tip. The limiting process requires using a very fine mesh around the crack tip making the scheme computationally very expensive. It is shown that the behavior of K as a function of frequency is very similar to a modal response. Taking advantage of this, a more efficient scheme involves a modal analysis of the cracked sheet and scaling the response to that of the static stress intensity. In this way, only a static K calibration need be performed. All the examples shown are for a frequency range spanning multiple resonances and with two levels of damping.