1 Stress echocardiogram: This is an echocardiogram that is performed while the person exercises on a treadmill or stationary bicycle. 2  This test can be used to visualize the motion of the heart's walls and pumping action when the heart is stressed.
Viruses require an active host program to cause damage and infect other executable files or documents, while worms are stand-alone malicious programs that can self-replicate and propagate via computer networks, without human help.
The most common blunder people make when the topic of a computer virus arises is to refer to a worm or Trojan horse as a virus. One common mistake that people make when the topic of a computer virus arises is to refer to a worm or Trojan horse as a virus.While the words Trojan, worm and virus are often used interchangeably, they are not exactly the same thing. worm is similar to a virus by design and is considered to be a sub-class of a virus. Worms spread from computer to computer, but unlike a virus, it has the capability to travel without any human action.