Mites and Wee Beasties

Abstract

The subtitle of this paper could be “Humans versus Arthropods.” Of the several classes of arthropods, Arachnida and Insecta are the most important from the public health standpoint. Arthropods are among man's most formidable competitors and they can affect the health of humans by being vectors of pathogenic microorganisms, by invading tissues, by inoculating poisonous substances, and by being pests.

A review is made of public health aspects of some arthropods that might be seen on a university or college campus. The diseases and infestations caused by mites (scabies), lice (pediculosis), bed bugs, fleas, and ticks are discussed.     

Power-Law Adjusted Survival Models

A simple adjustment to parametric failure-time distributions, which allows for much greater flexibility in the shape of the hazard-rate function, is considered. Analytical expressions for the distributions of the power-law adjusted Weibull, gamma, log-gamma, generalized gamma, lognormal, and Pareto distributions are given. Most of these allow for bathtub-shaped and other multi-modal forms of the hazard rate. The new distributions are fitted to real failure-time data which exhibit a multi-modal hazard-rate function and the fits are compared.     

Robustness estimators of location:a classification of linear and adaptive estimators

Real-world data sets may be described in terms similar to trauma cases- 'messy' with 'high morbidity'. Alternative estimators to the traditional mean are examined via a simulation study over a wide range of both symmetric and asymmetric distributions. These alternative estimators are data depenmdent and, in most cases, represent data far better than the usual mean. Princeton and post-Princeton linear and adaptive estimators of location are summarized, and a classification scheme based on an ancillary or selector statistic is proposed. The computational formulae for the collection of estimators have been standardized, as have the ancillary statistics. We classify these estimators by their computational form, give the computational formulae for each in a standardized notation, evaluate the subclass of estimators, and identify our 'winner' in that class.     

Robust Two-Sample Statistics for Testing Equality of Means: a Simulation Study

When testing the equality of the means from two independent normally distributed populations given that the variances of the two populations are unknown but assumed equal, the classical two-sample t-test is recommended. If the underlying population distributions are normal with unequal and unknown variances, either Welch's t-statistic or Satterthwaite's Approximate F-test is suggested. However, Welch's procedure is non-robust under most non-normal distributions. There is a variable tolerance level around the strict assumptions of data independence, homogeneity of variances and normality of the distributions. Few textbooks offer alternatives when one or more of the underlying assumptions are not defensible.     

Present positions and future prospects in management science

This paper offers some thoughts on the present state of management science as a discipline and a profession, and considers possible developmental strategies. The growth of management science, and the optimism this engendered, was largely premised on the successful use of scientific methodology and quantitative techniques to solve a relatively narrow range of management problems. In the 1970s, however, this positivist/quantitative ‘traditional management science’ became subject to increasing critical assault from those who wanted to broaden the impact of the discipline. Alternative management science approaches were born—soft systems thinking, organisational cybernetics, critical management science—and succeeded in establishing themselves. The existence of these alternative strands of work, alongside traditional management science, raises important questions about the future development of the discipline and profession. In this paper four developmental possibilities are set down and examined to see what future prospects they hold out for management science. It is argued that three of these—the isolationist, imperialist and pragmatist strategies—would lead the discipline into a dead end. A pluralist option, however, offers excellent opportunities for successful, future development.     

Relationships between physical activity and the proximity of exercise facilities and home exercise equipment used by undergraduate university students

The authors used stratified random sampling procedures to investigate the relationships among physical activity (PA), the proximity of exercise facilities, and the quantity of home exercise equipment in a sample of 411 undergraduates. To examine the data they collected from the modified Godin Leisure-Time Exercise Questionnaire and the Home Environment Questionnaire, the authors used correlational analyses and analysis of variance. Intensity and duration of PA showed a significant relationship to the proximity of exercise facilities. Intensity, frequency, and duration of PA were significantly related to the quantity of students' home exercise equipment. Freshmen and sophomores engaged in PA closer to their residences and participated in 3 more exercise bouts per week than juniors and seniors. These findings suggest that proximity of the activity episode may have an effect on PA behavior of college students.     

The simulation of industrial robot systems

This paper describes the GRASP computer aided design system for modelling and evaluating industrial robot workplaces. GRASP satisfies a range of simulation needs within the context of designing, implementing and operating industrial robotic systems. The GRASP software may be used to investigate robots operating by themselves or, more likely, as part of an integrated cell. Facilities within GRASP assist workplace layout, position and velocity evaluations, clash detection and co-ordination between items. A robot library exists and is being extended, and an embryo off-line programming facility has been used under restricted conditions. GRASP has been used to help solve a wide range of practical industrial robot problems and has proved itself technically, and also as an educational tool, by showing how a proposed system would operate. The paper describes the facilities within GRASP.     

The impact of marriage on fertility intentions and related values

Entry into and occupancy of major adult roles are of longstanding theoretical interest, but few studies have designs adequate to examine the consequences of associated changes in orientation. This study is based on a longitudinal project in which changes in fertility intentions and the importance of marriage and the family are examined among four subgroups--females who remained single, females who married, males who remained single, and males who married over a five-year period. Females, regardless of marital status, became less inclined to have children, males remaining single became more inclined and males who married over the interval changed little. When a control for value of marriage and the family was introduced, gender-based differences in fertility desires disappeared. There were substantial changes in the value domain according to sex and marital status--those who married over the five-year period displayed significant increases in the importance of the value of marriage and family. The implications of these findings are discussed.