Many rare event searches including dark matter direct detection and neutrinoless double beta decay experiments take advantage of the high VUV reflective surfaces made from polytetrafluoroethylene (PTFE) reflector materials to achieve high light collection efficiency in their detectors. As the detectors have grown in size over the past decade, there has also been an increased need for ever thinner detector walls without significant loss in reflectance to reduce dead volumes around active noble liquids, outgassing, and potential backgrounds. We report on the experimental results to measure the dependence of the reflectance on thickness of two PTFE samples at wavelengths near 178 nm. No change in reflectance was observed as the wall thickness of a cylindrically shaped PTFE vessel immersed in liquid xenon was varied between 1 mm and 9.5 mm.

Serum inhibitory titers to the agglutination of chicken red cells by vaccinial hemagglutinin have been measured in persons with a variety of chronic diseases and in a control sample of the general population. Between the ages of 30 and 74, elevated titers occurred in 63 per cent of the men and 56 per cent of the women with chronic diseases, but in only 40 per cent of the men and 36 per cent of the women in the "control" population. Patients with coronary heart disease tended to show the highest titers. The suggestion is made that the serum inhibitor under study may reflect, in part, relatively "nonspecific" pathological changes and tissue responses provoked by various biological stresses and is a promising approach to the recognition of cardiovascular disease and related disorders.