[A survey of deployment of sidewalks in central urban areas of 12 cities, China].

Objective: To explore the deployment of sidewalks and the possible relationship with local GDP, population density and prosperity of streets in 12 cities selected in China. Methods: For all the streets in 333 blocks of 12 cities surveyed (Beijing, Tianjin, Shanghai, Qingdao, Hangzhou, Shaoxing, Suzhou, Nantong, Zhenjiang, Chengdu, Xining and Harbin), the deployment and management of sidewalks were observed. And we collected the GDP data of the 12 cities, the population data of 333 blocks, and the numbers of stores and restaurants along the streets. Results: A total of 4 255 streets were included in the study. In the 12 cities, 71.1% of the streets had sidewalks. The deployment rates of sidewalks was high in Qingdao (91.9%) and Harbin (90.6%), and low in Suzhou (48.6%) and Shaoxing (52.6%), the differences were significant. The higher GDP of city was, the more sidewalks were deployed. But on the other hand there were more parking cars and obstacles on the sidewalks. The higher the population density was, the worse the condition of sidewalks was. Conclusions: The survey of sidewalks in the 12 cities indicated that efforts could be made to improve the condition of sidewalks. Attention should be paid not only to the deployment of sidewalks, but also the management of sidewalks. Reasonable deployment of sidewalks should be considered according to the local population density and traffic flow.

Electro-optical effect of a magnetically biased ferronematic liquid crystal.

The electro-optical effect of a magnetically biased ferronematic liquid-crystal film is investigated by using birefringence measurements. When a magnetic field is applied, the threshold voltage of the Freedericksz transition no longer exists. The dependence of the birefringence on the magnetic field strength in the low field regime is presented. A theory that accounts for the results is given.