A further note on a theorem on the difference of the generalized inverses of two nonnegative definite matrices

Andrews and Phillips (1986) gave a simplified proof for the result that established the nonnegative definiteness of the difference of the Moore-Penrose inverses of two nonoegative definite matrices, a result originally due to Milliken and Akdeniz (1977), The purpose of this paper is to offer a simple proof for a generalization of this result,     

Sleep hygiene practices and sleep duration in rotating-shift shiftworkers

Abstract

Alcohol, caffeine and tobacco intake, exercise, activities on going to bed, and sleep-enhancing measures were assessed in 72 rotating-shift shiftworkers to determine whether these variables differ following day shifts and night-shifts, and which are related to sleep duration. Only alcohol intake and exercise prior to sleep, and feeling drowsy when retiring, differed following the night-shift. Workers generally followed recommendations concerning alcohol intake, sleeping immediately on retiring, and exercising, but acted contrary to recommendations concerning caffeine and nicotine intake. The only behaviour clearly associated with poor sleep was smoking, which reduced sleep duration.     

TMR: An Automated System for Managing Revenue

Abstract

The Total Medical Record (TMR) system used by the Division of University Health Services at Duke University is an integrated medical and management information system. One module supports the financial needs of the division. To facilitate managerial performance, TMR automatically prints insurance claims, refund statements, revenue summary data, service utilization, itemized visit statements, monthly patient bills, dunning letters, and has a host of unique features that aid management with controlling the private fees generated by the University Health Services. In addition, the servicing of prepaid programs is accommodated, and the splitting of charges between prepaid and fee-for-service programs occurs automatically.     

An industrial application for total productivity optimization

Abstract. This paper presents four strategies for total productivity optimization of a real-life manufacturing company. These strategies are developed to attain overall growth, cost reduction, upgrading of technical efficiency and management effectiveness. Such strategies have been modelled mathematically by using a nonlinear mathematical programming approach. The model base and the data base used in implementing the strategies can serve as decision support to management for optimizing total productivity.     

Children’s Experiences of Completing a Computer‐Based Violence Survey: Ethical Implications

This article aims to contribute to the discussion about the ethics of research on children when studying sensitive issues such as violence. The empirical analysis is based on the accounts given by children (11 377) who completed a computer‐based questionnaire about their experiences of violence (‘The Finnish Child Victim Survey 2008’) and their reflections on the survey. We argue that experiences of violence should not be excluded from the research agenda on children due to ethical reasons, but that a more sophisticated practice should be developed instead to meet the needs and rights of children as informants. © 2010 The Author(s). Journal compilation 2010 National Children’s Bureau and Blackwell Publishing Limited.     

Book reviews and books received

Abstract

In the field of stress research it is often assumed that social support as well as coping behaviour contributes to feelings of health and well-being. However, until now it has not been altogether clear whether a main-effect model or a buffer model was the more appropriate for explaining the role of these factors in response to stressful situations. In this paper, a research project is described in which both the direct and indirect effects of social support and coping were studied in the work situation of nurses. The results offer more support for a main-effect model than for a buffer or moderating-effect model, especially with regard to the coping strategies ‘active problem-solving’ and ‘palliative behaviour’. However, some moderating effects on nurses‘ reactions to their work situation were found for social support and for ‘comforting cognitions’ as a coping strategy.     

Katrina in historical context: environment and migration in the U.S.

The massive publicity surrounding the exodus of residents from New Orleans spurred by Hurricane Katrina has encouraged interest in the ways that past migration in the U.S. has been shaped by environmental factors. So has Timothy Egan’s exciting book, The Worst Hard Time: The Untold Story of those who survived the Great American Dust Bowl. This article places those dramatic stories into a much less exciting context, demonstrating that the kinds of environmental factors exemplified by Katrina and the Dust Bowl are dwarfed in importance and frequency by the other ways that environment has both impeded and assisted the forces of migration. We accomplish this goal by enumerating four types of environmental influence on migration in the U.S.: (1) environmental calamities, including floods, hurricanes, earthquakes, and tornadoes, (2) environmental hardships and their obverse, short-term environmental benefits, including both drought and short periods of favorable weather, (3) environmental amenities, including warmth, sun, and proximity to water or mountains, and (4) environmental barriers and their management, including heat, air conditioning, flood control, drainage, and irrigation. In U.S. history, all four of these have driven migration flows in one direction or another. Placing Katrina into this historical context is an important task, both because the environmental calamities of which Katrina is an example are relatively rare and have not had a wide impact, and because focusing on them defers interest from the other kinds of environmental impacts, whose effect on migration may have been stronger and more persistent, though less dramatic.     

Understanding information systems infrastructure in engineering SMEs: A case study

The benefits of integrated enterprise-wide information systems (IS), such as Enterprise Resource Planning (ERP) systems, are widely accepted. The implementation of such systems in large organisations is established with many in their second or third generation. However, in small to medium-sized enterprises (SMEs) the maturity and extent of their IS infrastructure is less clear. In engineering SMEs, this infrastructure needs to support not only business processes but also the activities of design and manufacture.In this case study, our goal is to provide a better understanding of current IS infrastructure, the functional elements of IS infrastructure, integration and expenditures are explored in ten engineering SMEs. A model of IS functionality is developed and used to identify and classify functional elements within the firms and to compare and contrast the IS infrastructures. The findings are contrasted with the SME literature and conclusions and implications developed.