The minimal transformation to orthonormality

The solution is presented to the problem of finding that orthonormal matrix closest in the least-square sense to a given matrix of full rank. An application is shown to the problem in multiple regression analysis of determining the importance of each independent variable.     

An experimental approach to the design of cartographic symbols

Graphic designers and an experimental psychologist worked together to improve the design of two map symbols which are frequently confused: the symbols for cuttings and embankments on topographic maps. The problem was analysed in terms of the function of the symbols and their likely cognitive representations. Tests were developed to evaluate alternative designs, including an intervisibility task which requirred users to visualize the landform from the symbols viewed in the context of a map. Tests were given to schoolchildren and to experienced map users in order to compare the standard symbols with five alternative designs. Children's performance was strongly affected by the symbols they used, but experienced users were much less affected. After some refinement of the symbols a further experiment demonstrated the superiority of a number of alternative designs over the existing symbols on a range of test: scores were almost double on the intervisibility task. The paper makes recommendations to cartographers and argues for greater consideration of the inexperienced map user in the design process.     

Simple knowledge structures for perceptual classification expert systems

A new approach is described for the development and structure of perceptual knowledge-based systems. This systematic method for acquiring perceptual knowledge for use in knowledge-based systems and for representing perceptual knowledge within the systems has revealed that two broad classes of perceptual activity can each be characterized by a single logical operator. The number of rules necessary to accomplish particular perceptual tasks can also be estimated.     

HIV Disease: Current Concepts

The human immunodeficiency virus (HIV) causes a chronic, progressive, immune deficiency disease, the most severe phase of which is Acquired Immune Deficiency Syndrome (AIDS). HIV is a newly characterized human retrovirus transmitted only by direct exposure to blood or blood derivatives, certain acts of sexual intercourse, or transfer from infected mother to fetus or infant. In this article the author reviews the most important current epidemiologic, clinical, and virologic information about HIV and HIV disease and provides a factual framework for understanding the issues created by the epidemic.     

Distinguishing deviant and non-deviant nurses using the personnel reaction blank

Personnel Reaction Blank (PRB) scores and biographical data were obtained from two groups of registered nurses; a deviant group, represented by those who had official actions taken against their nursing license by the Minnesota Board of Nursing (n=53) and a non-deviant group of nurses (n=79) randomly selected from a broader population. The hypothesis that the deviant group of nurses would exhibit lower PRB scores, on average, compared to the non-deviant group was confirmed. The mean PRB scores for the deviant nurses (m=32.43) were significantly lower (p.01) than for the randomly selected non-deviant nurses (m=35.06). A multiple regression logit analysis showed that in addition to PRB scores, college degree, sex, and household income variables were also significantly related (p.001) to deviant and non-deviant group assignment; nonetheless, PRB significantly differentiated these groups after holding these variables constant.This study is based on the Masters thesis research of the first author. We acknowledge the help of the study subjects who contributed their time and effort.