Osteoarthritis (OA) . OA is the wear-and-tear arthritis that usually occurs with aging or after injury. With OA, there's a wearing down of the cartilage that cushions the ends of the bones. OA causes joint swelling in those joints that bear weight over a lifetime, such as knees, hips, feet, and spine.
During the Zhou dynasty, the Chinese developed irrigation and flood- control systems. As a result, farmers could grow more crops than ever before. Because more food could support more people, the population increased. During the late Zhou dynasty, China's population had expanded to about 50 million people. Zhou people also learned to use iron, which was cheaper and stronger than bronze. Iron weapons, the catapult and China's first cavalry (military on horseback) were some of the Zhou achievements that helped strengthen the army.
The most important of the changes that brought about the Industrial Revolution were (1) the invention of machines to do the work of hand tools; (2) the use of steam, and later of other kinds of power, in place of the muscles of human beings and of animals; and (3) the adoption of the factory system.he machines of the Industrial Revolution in the 18th and early 19th centuries were simple, mechanical devices compared with the industrial technology that followed. Many new products were devised, and important advances were made in the system of mass production.