Central nervous system malformations in relation to two polyvinyl chloride production facilities.

A modified case-control study was conducted for selected birth defects that occurred among residents who lived in areas that surrounded two vinyl chloride polymerization facilities in New Jersey. Odds ratios for central nervous system defects (ICD 9, 740-742) decreased as the distance the mothers' residences were located from the facilities increased. Higher odds ratios for central nervous system birth defects were found in the areas around the plant that had higher vinyl chloride emissions. None of the odds ratios, however, were statistically significant. The differences in concentrations of emissions from the different plants may contribute to the discrepancies reported in previous studies wherein the risk of environmental exposure to vinyl chloride was assessed.

Multicomponent frequency shifting self-aligning laser velocimeters.

A design using simple lenses and frequency shift by scattering disk has been developed, which allows easy construction, and alignment of one-, two-, and three-orthogonal-component, frequency shifting laser Doppler velocimeters. A series of instruments designed on this basis have proved to be inexpensive to construct, precise and accurate to use, adaptable to a wide range of applications, and have proven particularly advantageous in studies of turbulent phenomena and complex flows. In this paper the design concept is explained, construction and alignment procedures are outlined for the simplest assembly of the one and two component versions, and performance and application examples are presented. The extension of the system to measure the third orthogonal component is discussed.