[Incidence and prognosis of intra-and extracranial large-artery stenosis in the rural community of Beijing].

Objective: To assess the prevalence rates of intra- and extracranial large-artery stenosis in the rural community population and its related risk to the development of stroke.

Methods: The study subjects included 1337 residents in the rural community of Beijing. Transcranial Doppler was carried our to examine the relation between intra- and extracranial large-artery stenosis and subsequent cerebrovascular events, with a mean follow-up period of 16.

Humidity effect on the decay of second-order nonlinearity in thermally poled fused silica.

Type I (GE124) and Type II (KV) fused silica were thermally poled in a vacuum and in air under identical poling conditions. Second-order nonlinear (SON) strength and nonlinear depth were found all to be the same. Samples were then stored in high and low humidity to study their SON stability.