Acoustic emission for on-line reactor monitoring: Results of intermediate vessel test monitoring and reactor hot functional testing

This article discusses a program designed to develop the use of acoustic emission (AE) methods for continuous surveillance to detect and evaluate flaw growth in reactor pressure boundaries. Technology developed in the laboratory for identifying AE from crack growth and for using that AE information to estimate flaw severity is now being evaluated on an intermediate vessel test and on a reactor facility.A vessel, designated ZB-1, has been tested under fatigue loading with simulated reactor conditions at Mannheim, West Germany, in collaboration with the German Materialprüfungsanstalt (MPA), Stuttgart. Fatigue cracking from machined flaws and in a fabrication weld were both detected clearly by AE.AE data were measured on a US nuclear reactor (Watts Bar, Unit 1) during hot functional preservice testing. This demonstrated that coolant flow noise is a manageable problem and that AE can be detected under operational coolant flow and temperature conditions.     

Penumopericardium due to transdiaphragmatic perforation of a gastric ulcer

A 65-year-old man presented with cardiogenic shock and massive pneumopericardium. A gastropericardial fistula due to transdiaphragmatic penetration of a large fundal ulcer was documented radiographically and confirmed at autopsy. Previously recorded cases of penumopericardium complicating gastric ulcers or other diseases of the digestive tract are briefly reviewed.     

An analytical study on the effect of rigid body translational degree of freedom on the vibration characteristics of elastically constrained rotating disks

This study concerns the linear vibration behavior of annular spinning disk whose inner boundary is free to move in the axial direction while the body of the disk is constrained by a space fixed linear spring. It is shown, using analytical techniques based upon a three mode approximation, that constraining a spinning disk, free to have rigid body translation, with one space fixed spring does not change the critical speeds. Using an analysis, based on a two-mode approximation, the stability characteristics of a guided spinning disk due to the interaction between a rigid body translational mode and a forward or backward or reflected traveling wave are studied. It is shown that the interaction between the rigid body translational mode and a forward or backward traveling wave does not induce instability. In contrast to this situation it is shown that when the rigid body translational degree of freedom interacts with a reflected wave, depending on the speed and the stiffness of the spring, it may induce instability.     

Longitudinal assessment of growth in children born to mothers with human immunodeficiency virus infection

OBJECTIVES: To describe and to evaluate the longitudinal growth of children born to mothers with human immunodeficiency virus (HIV) infection. DESIGN: Measurements of weight, length (measured in infants in a recumbent position) and height (measured in older children in an upright position), and head circumference were documented and evaluated longitudinally using generalized estimating equations in a group of children born to HIV-infected mothers. Children infected with HIV were compared with uninfected children and with National Center for Health Statistics standards. SETTING: Primary care clinic in an urban hospital devoted to the medical care of children born to HIV-infected mothers. PATIENTS: One hundred nine children born to HIV-infected mothers, 59 HIV-infected and 50 uninfected, between birth and 70 months of age. RESULTS: The mean birth weights of both groups were below the 50th percentile. While the mean weight-for-age curve of uninfected children attained the 50th percentile by age 24 months, the mean birth weight-for-age curve of HIV-infected children remained below the 50th percentile. Weight gain became significantly different between the two groups by age 36 months. The mean birth length-for-age curves of HIV-infected and uninfected children was also below the 50th percentile. The mean height-for-age curve of uninfected children attained the 50th percentile by age 40 months, while that of HIV-infected children remained well below the 50th percentile. Linear growth between HIV-infected and uninfected children diverged earlier than weight, becoming significantly different by age 15 months. CONCLUSIONS: Although children born to HIV-infected mothers are born with weight and length below the 50th percentile, uninfected children catch up, while HIV-infected children remain below the 50th percentile and experience an earlier and more pronounced decrease in linear growth (height-for-age) than in weight-for-age.     

Assessment of medical technology: the role of engineers

Assessment of medical technologies is a multidisciplinary activity requiring the participation of engineers, clinicians and social scientists. The contribution of engineers has often been confined to the early stages of technical assessment. However, engineers have important inputs to make throughout the assessment process in their roles of developers, users and managers of technology. Engineers have found collaboration with clinical researchers possible through hospital-based work, but must also develop links with economists and other social scientists if they are to make a full contribution to comprehensive technology assessment.     

Cost-benefit and cost-effectiveness analysis in health care. Growth and composition of the literature

Concern about the escalating costs of health services is reflected in the rapid growth of the literature on cost-benefit and cost-effectiveness analysis (CBA and CEA, respectively) in health care. A search of that literature for 1966--78 produced a bibliography of more than 500 relevant references, growing from half a dozen per year at the beginning of the period to close to 100 each of the most recent 2 years. The literature growth has been more rapid in medical than nonmedical journals and a preference for CEA over CBA appears to be emerging. Studies related to diagnosis and treatment have gained in popularity, while the early prominence of studies with a substantive prevention theme has diminished. Consistent with the increasing medical focus of the literature, numbers of articles oriented toward individual practitioner decision making have grown more rapidly than those oriented toward organizational or societal decision making. In addition to documenting these trends, this article identifies published reviews of health care CBA/CEA and books and articles attempting to convey the principles of CBA/CEA to the health care community. The article concludes with speculation on likely near-future trends in the literature and consideration of the quality implications of the rapid growth.