We present a clustering algorithm which is unsupervised, incremental, and hierarchical. The algorithm is distance-based and creates centroids. Then we combine the power of evolutionary forces with the clustering algorithm, counting on good clusterings to evolve to yet better ones. We apply our approach to standard data sets, and get very good results. Finally, we use bagging to pool the results of different clustering trials, and again get very good results.
Twenty-two patients were studied during hospital admission for cardiac catheterization. Two independent observers rated their behavior at 15-min intervals over the 3-hour catheterization procedure in categories of affect, arousal and degree of interpersonal engagement. These rated data were used together with information obtained from retrospective interviews to assign each patient to one of the behavioral groups designated anxious-engaged, anxious-not engaged, depressed and calm. Plasma levels of growth hormone, cortisol, free fatty acid and glucose were determined every 30 min during the procedure. Free fatty acid levels rose appreciably in all patients. Calm and depressed patients showed no significant increases in plasma levels of either growth hormone or cortisol. Anxious-engaged patients showed elevations of cortisol but no elevation of growth hormone. Anxious-not engaged patients showed elevations of both growth hormone and cortisol. The several patterns of hormonal change may reflect different neural organizations underlying the several types of coping behavior.Plasma growth hormone levels in man are labile and have been shown to increase in response to different stimuli such as insulin-induced hypoglycemia, surgical pro-
Meaningful information was available on 26 patients who died suddenly in a 44,000 industrial population. The data, past illnesses, prodromal symptoms, and psychosocial information were obtained from the plant medical records, the private physicians, and mainly from direct interviews with the surviving next-of-kin, usually the wife. The data suggest that the majority of these patients, all men, had been depressed for a week up to several months. The sudden death then occurred in a setting of acute arousal engendered by increased work and activity or circumstances precipitating reactions of anxiety or anger. The findings suggest that the combination of depressive and arousal psychological states or abrupt transition from one such state to another may produce disharmonious responses in the hormonal and autonomic nervous systems, as well as central nervous system mediated behavior, which are conducive to the sudden death.The focus of my presentation is psychological variables in rela¬ tion to sudden death. The patients whom I describe have already been described in some detail in Gold¬ stein's presentation1 since the pre¬ hospital trio involved in the study of myocardial infarction at a pictur¬ esque industrial plant in Rochester, NY, includes Dr. Goldstein, Dr. Moss, and myself. My own main concern has been with psychosocial variables in both the on-work part of the study (those employees reporting to the in¬ dustrial plant medical facility with symptoms indicating a myocardial in¬ farction) and the so-called off-work part of the study (those reporting to nonplant medical facilities such as personal physicians, hospital emer¬ gency, or ambulance call). These two groups comprise all those with symp¬ toms of suspect or actual myocardial infarction who get to the hospital alive. The study of this total indus¬ trial population also includes those who die suddenly, within 24 hours of onset of significant development or change of symptoms.My interest in these psychosocial aspects evolved during a study with Dr. Moss of the adjustment of pa¬ tients with cardiac pacemakers in the course of which we took note of psy¬ chological factors occurring in rela¬ tion to the onset of symptoms at the time of development of varying de¬ grees of heart block with dizziness or syncope. In many, the symptoms of heart block developed in psychologi¬ cally distressful situations, chiefly those of depression.2 A later investi¬ gation, undertaken with the cardiol¬ ogists four years ago, of patients with heart disease, congenital and ac¬ quired, subjected to cardiac catheterization, showed differences in behav¬ ioral reactions to the threat of the catheterization procedure which could be correlated with variations in corti¬ sol and growth hormone changes.3 Such behavioral and hormonal differ¬ ences in turn have recently been shown to be correlated with sub¬ sequent morbidity and mortality, es¬ pecially in relation to cardiac sur¬ gery.4 I have also had a long background of interest in problems pertaining to the psychophysiology of the cardiovasc...
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