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A Lebedeff-type double beam interference microscope has been used to measure the three principal refractive indices of the photoconductor p-diiodobenzene and to observe the behavior of each of these refractive indices as the crystal undergoes a polymorphic phase transition to a structure characterized by markedly lower charge carrier mobility. The refractive index data permit the calculation, for each principal vibration direction, of the change in polarizability accompanying the phase transition. These polarizability results suggest that the phase transition results in a decreased intermolecular orbital overlap which, in turn, narrows the p-type conduction band. This interpretation would account for the sharp drop in hole carrier mobility which accompanies the phase transition.

The relation between vasectomy and renal disease was examined in the data collection phase of a study of vasectomy and coronary artery disease. The date of onset and type of urological disease was obtained for 11,205 men enrolled in the US Coronary Artery Surgery Study. Urolithiasis was the most common reported urological disease. The relative risk for calculi in men who had had a vasectomy ranged from 2.6 for patients 30-35 years old to 1.3 for those aged 55-65. The age-adjusted relative risk was 1.67 (p less than 0.001).

We compared the results of coronary artery bypass surgery with those of medical therapy alone in 1491 nonrandomized patients 65 years of age or older. Cumulative survival at six years (adjusted for major differences in important base-line characteristics) was 79 per cent in the surgical group and 64 per cent in the medical group (P less than 0.0001). At five years, chest pain was absent in 62 per cent of the surgical group and 29 per cent of the medical group (P less than 0.0001). Analysis by the Cox proportional-hazards model suggested an independent beneficial effect of surgery on survival (P less than 0.0001). Patients were divided into risk quartiles on the basis of preoperative predictors of survival identified by the Cox model. Surgical benefit was greatest in "high-risk" patients (those in the two quartiles containing patients with the poorest prognosis). Among 234 "low-risk" patients with mild angina, relatively good ventricular function, and no left main coronary artery disease, there was no survival difference between those treated medically and those treated surgically. We conclude that in specific higher-risk subsets of non-randomized patients 65 years of age or older, coronary bypass surgery appeared to improve survival and symptoms in comparison with medical therapy alone. These conclusions must be tempered by consideration of the limitations of nonrandomized studies, particularly since patients in the two treatment groups differed substantially with regard to important base-line characteristics.