No one really likes going to the doctor, but sooner or later, we all must go. Some people are very afraid, however, and fear getting ill while waiting for their doctor in a room full of sick people. Some fear the bad news they might receive or the procedure they have to undergo. Many people are...

Archimedes designed the first screw conveyor in third century B.C., it was used to remove water from ships and to irrigate farmland. The equipment itself has evolved over time but the practical use is the same; with each turn of the screw, a fixed volume of material is discharged. The main...