RESUMO
Objective To assess the prevalence rates of intra-and extraeranial 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 meall follow-up period of 16.7 months.Results The incidence densities of cerebral infarction and cerebral hemorrhage in persons without cerebral large-artery stenosis were 410.6 and 351.9/100-thousand person-years,respectively.In the group wlth large-artery stenosis,the incidence density of cerebral infarction was 3303.7/100-thousand person-years.Data from The Fisher's Exact test showed a significant difference in the two groups (P=0.004).Cerebral large-artery stenosis(OR=6.593,95%CI:1.712-25.390)and smoking (OR=8.437,95% CI:2.327-30.598)appeared to be independent risk factors to cerebral infarction.Conclusion Cerebral large-artery stenosis and smoking were independent risk factors to cerebral infarction.
RESUMO
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. The SON of poled GE124 was stable over time despite different poling atmospheres and humidity in storage. The SON of both the air-poled and vacuum-poled KV samples decayed over time in both low and high humidity, with the exception that the air-poled KV sample stored in low humidity remained stable. High humidity accelerated the decay process of the KV samples. A porous surface model was used to interpret the decay mechanism. The decay curves implied multiple carriers or a multiple-porosity model for the decay mechanism.
