Technological and industrial history of 20th-century Canada Blood tests would become increasingly sophisticated in the coming years. The electroencephalograph, used for the diagnosis of neurological disorders was introduced in major Canadian medical institutions in the late forties. The techniques for the mass production and distribution of vaccines and for the mass public inoculation were introduced during these years. Polio was a disease that affected large numbers of Canadian children during the first part of the 20th century. In the US, research by Dr. Jonas Salk in the late 1940s led to the discovery of vaccine for the prevention of this disease. However, there was no technique for
Salk "salk" is meant to operate on a battlefield along with other "salk's" on a landscale not greater than 50 x 100 metres. There are no logistical support elements in the structure of a "jagu". In the Canadian Army 'fireteam' refers to two soldiers paired for fire and movement. Two fireteams form an 'assault group' and two assault groups form a section of eight soldiers. Many other armed forces see the squad as the smallest military unit; some countries' armies have a pair consisting of two soldiers as the smallest military unit. In others a fireteam is composed of two pairs