Variability in Physical Constant Parameter Values from Standard Data Sources and the Implication of This Variability for Risk Analysis

Physical property values are used in environmental risk assessments to estimate media and risk-based concentrations. However, considerable variability has recently been reported with such values. To evaluate potential variability in physical parameter values supporting a variety of regulatory programs, eight data sources were chosen for evaluation, and chemicals appearing in at least four sources were selected. There were 755 chemicals chosen. In addition, chemicals in seven environmentally important subgroups were also identified for evaluation. Nine parameters were selected for analysis-molecular weight (MolWt), melting point (MeltPt), boiling point (BoilPt), vapor pressure (VP), water solubility (AqSOL), Henry's law constant (HLC), octanol-water partition coefficient (Kow), and diffusion coefficients in air (Dair) and water (Dwater). Results show that while 71% of constituents had equal MolWts across data sources, <3% of the constituents had equivalent parameter values across data sources for AqSOL, VP, or HLC. Considerable dissimilarity between certain sources was also observed. Furthermore, measures of dispersion showed considerable variation in data sets for Kow, VP, AqSOL, and HLC compared to measures for MolWt, MeltPt, BoilPt, or Dwater. The magnitude of the observed variability was also noteworthy. For example, the 95th percentile ratio of maximum/minimum parameter values ranged from 1.0 for MolWt to well over 1.0E + 06 for VP, and HLC. Risk and exposure metrics also varied by similar magnitudes. Results with environmentally important subgroups were similar. These results show that there is considerable variability in physical parameter values from standard sources, and that the observed variability could affect potential risk estimates and perhaps risk management decisions.     

Career Planning Validity of Self‐Estimates and Test Estimates of Work‐Relevant Abilities

This study sought to determine whether self‐estimates of work‐relevant abilities can improve upon the validity of test estimates (scores). Validity for career planning applications was the focus. The study (final sample of 1,620 college students) used 9 self‐estimates and test estimates to predict certainty‐screened occupational choices grouped by J. L. Holland (1997) types. The addition of ability self‐estimates to test estimates substantially improved upon the validity of test estimates alone. Study results (together with previous research) suggest that ability self‐estimates can provide efficient additions or alternatives to test estimates during career planning, while substantially broadening the range of abilities under consideration.     

'Pressed for time'– the differential impacts of a 'time squeeze'

The ‘time squeeze’ is a phrase often used to describe contemporary concerns about a shortage of time and an acceleration of the pace of daily life. This paper reviews analysis of the Health and Lifestyle Survey (HALS), 1985 and 1992, and draws upon in‐depth semi‐structured interviews conducted with twenty British suburban households, in order to shed light on ‘senses’ of time squeeze. 75% of HALS respondents felt at least ‘somewhat’ pressed for time, with variables of occupation, gender, age and consumption significantly increasing senses of being ‘pressed for time’. This is not surprising given theories of the ‘time squeeze’. However, identification of variables only offers insights into isolated causal effects and does little to explain how or why so many respondents reported feeling ‘usually pressed for time’. Using interview data to help interpret the HALS findings, this paper identifies three mechanisms associated with the relationship between practices and time (volume, co‐ordination and allocation), suggesting that ‘harriedness’ represents multiple experiences of time (substantive, temporal dis‐organisation, and temporal density). In conclusion, it is argued that when investigating ‘harriedness’ it is necessary to recognise the different mechanisms that generate multiple experiences of time in order for analysis to move beyond one‐dimensional interpretations of the ‘time squeeze’, and in order to account for the relationship between social practices and their conduct within temporalities (or the rhythms of daily life).     

Driving and Symbolic Interaction1

Although it is a prominent feature of modern experience, driving has received little attention from sociologists. Yet social interaction between motorists is an integral part of the traffic situation. This paper explores its bases and some of its typical dynamics. Other sociologically relevant aspects of driving are delineated and the issue of how driving may influence modern culture is addressed.     

Parametric discounting

A parametric approach to the problem of selection from amongst alternative investment opportunities is considered in a discounted cash flow framework. The approach employs differential cash flows, an uncertain planning horizon and a nested approach to composing cash flow parameters. This promotes consistent treatment of alternative investments, clarifies the effects of uncertainty, avoids some of the defects of internal rate of return and payback period criteria and allows direct comparison of best and next best options as primal and dual versions of the same model. Net present value, internal rate of return, annual average cost or payback period assessments may be selected post analysis. A domestic wall insulation example is used for illustrative purposes. This example is related to the hydroelectric power development decision which gave rise to the approach.     

State and local government wage differentials: An intrastate analysis

Previous estimates of state and local government wage differentials have been typically based on data aggregated across all states, and such aggregation may produce seriously misleading differential estimates. We estimate intrastate earnings differentials for the state and local sectors in Wisconsin, four other midwestern states, and two states outside the midwest. There is substantial variation in the differentials: aggregated differentials can be misleading. Our work also confirms that state and local government labor markets have reduced earnings dispersion and investigates the possibility that higher public sector earnings may attract an “over-qualified” work force. The authors thank the Wisconsin Policy Research Institute for financial support and members of the UWM economics seminar and Sammis White for detailed comments on earlier drafts.     

A microcomputer simulation of an automated non ferrous sand casting foundry

In this paper the authors describe the simulation of an automated non ferrous sand casting foundry using a popular microcomputer to evaluate the effects on output of several machine loading rules. The programmed facilities allow the scheduler to experiment with his own loading rules on actual, rather than hypothetical, batches of jobs which, if found to increase output or some other measure of performance, can be stored for scheduling future jobs. Scheduling in such an interactive manner allows the simulation program to learn and improve upon scheduling rules on actual jobs in much the same way as the human scheduler would in practice, without the associated risks of affecting production.     

The interaction of aging and 10 years of racing on ultraendurance running performance

The aim of this study was to examine the interaction between aging and 10 years of racing in endurance runners. Race-time data from 194 runners who had completed 10 consecutive 56-km ultramarathons were obtained. The runners were either 20.5 +/- 0.7, 30.0 +/- 1.0, 39.9 +/- 0.9, or 49.4 +/- 1.0 years old at their first race. Each runner's race speed was determined for each race over the 10 years. Data were analyzed using repeated-measures ANOVA, one-way ANOVA, and independent t tests and showed that performance improved and declined at greater rates for younger runners; younger runners had a greater capacity for improvement than older runners; approximately 4 years were required to reach peak racing speed, regardless of age; it was not possible to compete at peak speed for more than a few years; and the combined effects of 10 years of aging and racing neither improve nor worsen net performance. In conclusion, these data suggest that although these runners showed similar patterns of change in race speed over a 10-year period, the extent of change in performance was greater in younger than in older runners.