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.
Once an error has made it into a database, it can easily be propagatedânot only around the original database, but into any number of other systems. âComputational analysis will propagate errors, as will transformation and integration of data from various public data resources,â Overton said. âPeople are starting to worry about this problem.