World energy resources and the limitations of computer modelling

The views of Meadows and the Club of Rome are challenged in the first part of this article, which reviews available information on world energy reserves. Here the conclusion is reached that the real nature of the energy ‘crisis’ is not one of impending resource exhaustion, but of economic, social and political problems stemming from rising prices and the uneven distribution of world reserves. Part Two takes up the question ‘How far are large computer models likely to be relevant for the formulation of energy policy?’ It concludes that they can be a useful tool for analysing complex relationships and portraying future scenarios, but they should not be seen as a substitute for policy choices.     

Some issues in the current debate about energy and natural resources

“Zero-growth policies to restore the planet to long-term physical equilibrium or reliance upon market forces to achieve equilibrium between demand and supply?” This sums up the opposing views in the current debate about resources and the environment. Unfortunately, both viewpoints show a disregard for the social and political implications and the uncertainties surrounding their basic assumptions. This article argues that little reliance can be placed upon the published estimates of world fuel and mineral resources, that the assumption of long-term exponential growth in demand for resources is highly contentious, and that it would be unwise to forego the fruits of economic growth owing to a rather remote possibility that global resource depletion may occur in the distant future. Long-term projections are necessary to illustrate what the future may hold, but Malthusian or any other computer models should not be substituted for policy choices. As far as possible, policies should take account of uncertainty and risk and the problems likely to arise from rising prices of fuels and minerals resources and from the location of the bulk of the known reserves of some resources in a few countries. Not least, the aim should be to pursue paths of economic growth which place lighter demands upon the earth's resources and to open desirable technical options for the future through research and development.     

Comparison of a simulated versus work environment lifting task on L5/S1 compression forces

Since a patient's ability to perform simulated work activities guides return-to-work decisions, a significant question to address is whether the simulated work environment accurately reflects the actual work environment. Work hardening programs have been used extensively as a method of rehabilitating workers to return to their pre-injury functioning levels. Re-training workers to lift boxes is a common method used to simulate the work environment. Although very few boxes used in the real work environment have handles, boxes with handles are often used in the simulated work environment. The difference in compression forces at the L5/S1 joint while lifting boxes with and without handles was investigated. The Lift Trak Motion Analysis system was used to estimate lumbar isometric compression forces exerted while lifting a 20-pound (9.07-kg) box. The results indicated that estimates of compression forces when lifting a box without handles were significantly different (p < 0.01) than when lifting the same box with handles. Based on these results, it is recommended that work hardening professionals carefully re-evaluate the simulated work environments currently being used for treatment.     

Efficiency, growth, and concentration: an empirical analysis of hospital markets

Taking an evolutionary view, Harold Demsetz hypothesized that firms differ persistently in efficiency and that industry concentration results from growth of efficient firms at the expense of inefficient ones. We test this idea with microdata from the hospital industry. Initial hospital efficiency and subsequent growth (and profitability) are significantly and positively related. Also, greater initial variation in hospital efficiency within local markets is positively related to subsequent growth in market concentration. Our findings support the evolutionary efficiency hypothesis, though they cannot confirm the stronger idea that variation in efficiency is the dominant explanation for changes in concentration.     

A comparison of performance outcomes between the Minnesota Rate of Manipulation Test and the Minnesota Manual Dexterity Test

This study examined the performance outcomes between two tests of manual dexterity, the Minnesota Rate of Manipulation Test [1] and the Minnesota Manual Dexterity Test (1981). Even though the tests are constructed differently and are different versions of the Complete Minnesota Dexterity tests, both tests utilize the same instruction manual and the same normative data. The researchers measured 233 random participants at a Midwestern international airport and in the student center at a local university in Indiana. Each participant completed three trials of a subtest on both versions of the test. One sample t-tests on difference scores indicated statistically significant differences on outcomes of both subtest comparisons as well as overall test score differences (p < 0.000). These significantly different outcomes on the two tests illustrate the need to establish separate normative data on the latest version of the test, the Minnesota Manual Dexterity Test.