The measurement of the time dependence of light scattered from a collection of moving particles, commonly referred to as quasi-elastic light scattering (QELS), provides information about the distribution of particle velocities. For monodisperse particles undergoing Brownian motion, the time dependence of the autocorrelation of the scattered light is a simple exponential function of the hydrodynamic radius of the particle. For polydisperse suspensions undergoing Brownian motion, the time dependence of the autocorrelation of the scattered light is a function of the particle-size distribution and can be expressed either as a Fredholm integral or a sum of exponentials. This paper describes improvements in the methods of data acquisition and analysis that significantly increase the resolution of the technique. These improvements enable accurate determinations and smooth representations of both bimodal and broad unimodal distributions without operator intervention or a priori information about the particle-size distribution.

We have used the atomic force microscope as a nanoindenter to both doped and undoped polycarbonate to probe the dependence of adhesion on topography and material inhomogeneities. Adhesion measurements at the same position are repeatable to 2%. The magnitude of the adhesion is found to decrease as the local curvature on the surface increases. Spatial adhesion maps of doped polymers show structure that is not apparent in surface topography. The spatial resolution of the measurement is at least 300 Å.

General Basic Comments Recommendations for Laboratory Testing in Children with Thrombosis Pediatric patients should be tested for a full panel of genetic and acquired prothrombotic traits. Detection of one thrombophilic factor does not exclude the existence of a second or third.

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