Abstract: The invention relates to a method using an optical cable tracker to measure optical cable distances and an optical cable tracker, which comprises a light source, an optical coupler, a phase modulator, a delay optical fiber, and an optical signal demodulation module. In the invention, optical cables are knocked to create disturbance. Not only can the optical cable be identified based on the corresponding interference produced by the light ray in optical cables, but also the distances from knock points to the local telecommunication terminals can be estimated. This facilitates the inspection, repair and maintenance of optical cables.

Abstract: A process of using Isatis root polysaccharide in the manufacture of medicaments for treating and/or preventing diseases induced by influenza virus and complications thereof, wherein the molecular weight of the Isatis root polysaccharide is 3000-7000 Da, and the influenza viruses include influenza virus A, influenza virus B, avian influenza virus, such as human influenza virus H1N1, H3N2, avian influenza virus H6N2, H7N3, H9N2 and INF B. The mechanism of the Isatis root polysaccharide against influenza virus is due to the ability to inhibit the attachment of influenza virus to the host cell. The present invention also discloses a pharmaceutical composition containing the above-mentioned Isatis root polysaccharides and a method for preparing the polysaccharides.